Maths 4 Mark Question

Draw any triangle on a paper. Name its vertices A, B, C. Measure the lengths of its three sides using a divider and scale and enter them in the table.

Length of side	Sum of the lengths of two sides	Length of the third side
l (AB) = cm	l (AB) + l (BC) = cm	l (AC) = cm
l (BC) = cm	l (BC) + l (AC) = cm	l (AB) = cm
l (AC) = cm	l (AC) + l (AB) = cm	l (BC) = cm

Properties of a triangle
Take a triangular piece of paper and make three different types of marks near the three angles. Take a point approximately at the center of the triangle. From this point, draw three lines that meet the three sides. Cut the paper along those lines. Place the three angles side by side as shown. See how the three angles of a triangle together form a straight angle, or, an angle that measures 180°.

Properties of a triangle.
Take a triangular piece of paper. Choose three different colors or signs to mark the three comers of the triangle on both sides of the paper. Fold the paper at the midpoints of two sides as observe?

Observe the set squares in your compass box. What kind of triangles are they?

Measure all the angles of the triangles given below. Enter them in the following table.

In ∆DEF	In ∆PQR	In ∆LMN
Measure of ∠D = m ∠D =___	Measure of ∠P = m ∠P =___	Measure of ∠L =__
Measure of ∠E = m ∠E =___	Measure of ∠Q =___=___	Measure of ∠M =___
Measure of ∠F = ___=___	Measure of ∠R =___=___	Measure of ∠N =___
Observation:All three angles are acute angles.	Observation:One angle is right angle and two are acute angles.	Observation:One angle is an obtuse angle and two are acute.

Measure the sides of the following triangles in centimeters, using a divider and ruler. Enter the lengths in the table below. What do you observe?

In ∆ABC	In ∆PQR	In ∆XYZ
l (AB) = cm	l (QR) = cm	l (XY) = cm
l (BC) = cm	l (PQ) = cm	l (YZ) = cm
l (AC) = cm	l (PR) = cm	l (XZ) = cm