Basic Drawing is the first presentation of a Technical Drawing course.

1. TECHNICAL
DRAWING I

2. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
POINT:
A No dimension.
C
B It’s a position.
Always in CAPITAL letters.

3. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
LINE: It’s an addition of several
points following the same
r
direction.
Always in small letters; r, s, t…
r r
s r
A s
s
Two lines cut each Two lines can be When the two lines
other when they share parallel when the share no point, they
a point. sharing point is in the cross each other.
infinite.

4. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
HALF LINE: One point is known and the
A
∞→ other is in the infinite.
r
A point in the line defines tow
←∞ A ∞→ half-lines, one to the left and
r the other to the right.
SEGMENT:
A B Is a kind of line defined
r between two known points.

5. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
CURVED LINE:
A curved line is a group of
points constantly changing
direction.
Always in small letters.

6. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
PLANE:
Is the set of points that arise when you move a straight
line in one direction.
We need the following information to define a plane:
Non aligned 3 points. Two lines cutting each other.
Two parallel lines. A line and a point out of the line.

7. THEME 2: BASIC PATHS IN THE PLANE
Lines within a plane:
Bisecting line:

8. THEME 2: BASIC PATHS IN THE PLANE
Lines within a plane:
To draw a perpendicular from “M” point outside the line:

9. THEME 2: BASIC PATHS IN THE PLANE
Lines within a plane:
To draw a perpendicular from “P” point inside the line:

10. THEME 2: BASIC PATHS IN THE PLANE
Lines within a plane:
To construct a perpendicular at the end of a given line:

11. THEME 2: BASIC PATHS IN THE PLANE
Lines within a plane:
● To draw parallel lines with the set squares:

12. THEME 2: BASIC PATHS IN THE PLANE
Lines within a plane:
● To draw perpendicular lines with the set squares:

13. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
ANGLES:
Is a measure of a turn. We use a protractor to measure an angle.
Sometimes we use letters from Greek alphabet to name angles; α, β, γ,
δ…
And sometimes we name (B) the vertex of the angle and (choosing A and C
points) on the two sides; we write ABC. So the angle reads ABC.
Different kind of angles:
Null angle: α = 0°
Acute angle: α < 90°
Right angle: α = 90°
Obtuse angle: α > 90°
Plain angle: α = 180°
Complete angle: α = 360°

14. THEME 2: BASIC PATHS IN THE PLANE
Basic geometrics elements:
ANGLES:
Two lines cutting each other at point O creates the following angles;
β
α γ
δ
 Adjacent angles: α and β. Same vertex and side in common.
 Angles opposite at vertex; α and γ; β and δ.
So, α and γ / β and δ are of the same value.

15. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
To construct an angle similar to a given angle;

16. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
Summing up angles;

17. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
Difference between angles;

18. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
To bisect an angle (bisector);

19. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
To bisect an angle (bisector);

20. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
Drawing angles;
60 angle: 90 angle:
45 angle: 30 angle:
15 angle: 75 angle:

21. THEME 2: BASIC PATHS IN THE PLANE
Operations with angles :
Drawing angles;
105 angle: 120 angle:
135 angle: 150 angle:

22. THEME 2: BASIC PATHS IN THE PLANE
Geometric places:
The set of points having the same geometric characteristics.
1. Circumference:
2. Bisecting line:

23. THEME 2: BASIC PATHS IN THE PLANE
Geometric places:
3. Bisector line:
4. The loci arc of a segment (depending on the angle):

24. THEME 2: BASIC PATHS IN THE PLANE
Circumference:
A circle is a plain figure bounded by a curved line called the
circumference, witch is always equidistant from the centre.
Lines of a circumference:
Radius; Any of the straight lines from the centre to
the circumferences. The radius is half the diameter of
the circumference.
Diameter: The longest possible chord of a
circumference. A line passing through the centre with
both ends touching the circumference.

25. THEME 2: BASIC PATHS IN THE PLANE
Circumference:
Chord: A straight line, witch each end touching the
circumference.
Arrow; It’s a part of the radius between the chord
and the circumference. The radius is perpendicular
to the chord.
Secant: A line that cuts the circumference at two
points.
Tangent: A line touching the circumference at one
point. Forms a right angle with a radius of the circle.
T is the point contact.

26. THEME 2: BASIC PATHS IN THE PLANE
Circumference:

27. THEME 2: BASIC PATHS IN THE PLANE
Circumference:
To construct a circumference when you have 3 points.

28. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
TRIANGLES:
Is a polygon formed by three segments.
The addition of every inner angles of a triangle is always 180º.
α + β + γ = 180º
The value of the outside angle of a triangle is the addition of
the two non-adjacent inside angles.

29. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
TRIANGLES:
In every triangle, any side is always smaller than the addition of
the other two;
a<b+c
And any side is larger than the subtraction of the other two;
b>a-c
In every triangle the larger angle is in front of the larger side;
c > a; γ > α

30. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
CLASSIFICATION OF TRIANGLES:
Depending on sides;
Equilateral: Isosceles: Scalene:

31. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
CLASSIFICATION OF TRIANGLES:
Depending on angles;
Acute:
Right:
Obtuse:

32. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
REMARKABLE LINES AND POINTS OF A TRIANGLE:
Bisector / Incentre / Inscribed circle to a triangle.

33. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
REMARKABLE LINES AND POINTS OF A TRIANGLE:
Bisecting line / Circumcentre / Circumscribed circle to a triangle.

34. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
REMARKABLE LINES AND POINTS OF A TRIANGLE:
Altitudes / Orthocentre.

35. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
REMARKABLE LINES AND POINTS OF A TRIANGLE:
Baricentre or Centre of Gravity.

36. THEME 3: TRIANGLES, SQUARES AND REGULAR POLYGONS
CONSTRUCTING TRIANGLES:
a) Knowing the 3
sides a, b and c.
b) Knowing 2 of the
sides and the angle
between them.
c) Knowing one
side, a, and the
angles B and C.

37. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
QUADRILATERAL:
It is an polygon formed by 4 sides.
QUADRILATERALS
Trapezium (two
PARALELOGRAM
sides are parallels, Trapezoid (no
(Two by two, sides
the other two parallel sides)
are parallel)
aren’t)

38. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
QUADRILATERAL:
Square
Rectangle.
PARALELOGRAM
(Two by two,
sides are parallel)
Rhombus.
Rhomboid

39. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
QUADRILATERAL:
Trapezium
(two sides are parallels, the other
two aren’t)
Isosceles
Right
Scalene

40. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
QUADRILATERAL:

41. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
What is a Polygon?
A closed plane figure made up of several line
segments that are joined together.
The sides do not cross each other.
Exactly two sides meet at every vertex.

42. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
One polygon is regular if all the sides and all the angles are equal.
l = Side.
a = Apoteme
r = Radius
α = 180º - (360º / n)
λ = 360º / n

43. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Regular Hexagon.

44. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Regular triangle; equilateral triangle.

45. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Dodecagon.

46. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Square.

47. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Octagon.

48. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Pentagon

49. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Decagon

50. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Heptagon

51. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
General way.

52. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Pentagon (knowing the the side)

53. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Hexagon (knowing the the side)

54. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Heptagon (knowing the the side)

55. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Octagon (knowing the the side)

56. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Nonagon, Enneagon (knowing the the side)

57. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
Decagon (knowing the the side)

58. THEME 3: TRIANGLES, QUADRILATERALS AND REGULAR POLYGONS
REGULAR POLYGONS:
General way
(knowing the
the side)