Exercise 10.2 - Chapter 10 - Practical Geometry - Ncert Solutions class 7 - Maths
Updated On 26-08-2025 By Lithanya
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Question 1:
Construct ΔXYZ in which XY = 4.5 cm, YZ = 5 cm and ZX = 6 cm.
Answer:
The rough figure of this triangle is as follows.
The required triangle is constructed as follows.
(i) Draw a line segment YZ of length 5 cm.
(ii) Point X is at a distance of 4.5 cm from point Y. Therefore, taking point Y as centre, draw an arc of 4.5 cm radius.
(iii) Point X is at a distance of 6 cm from point Z. Therefore, taking point Z as centre, draw an arc of 6 cm radius. Mark the point of intersection of the arcs as X. Join XY and XZ.
XYZ is the required triangle.
Question 2:
Construct an equilateral triangle of side 5.5 cm.
Answer:
An equilateral triangle of side 5.5 cm has to be constructed. We know that all sides of an equilateral triangle are of equal length. Therefore, a triangle ABC has to be constructed with AB = BC = CA = 5.5 cm.
The steps of construction are as follows.
(i) Draw a line segment BC of length 5.5 cm.
(ii) Taking point B as centre, draw an arc of 5.5 cm radius.
(iii) Taking point C as centre, draw an arc of 5.5 cm radius to meet the previous arc at point A.
(iv) Join A to B and C.
ABC is the required equilateral triangle.
Question 3:
Draw ΔPQR with PQ = 4 cm, QR = 3.5 cm and PR = 4 cm. What type of
triangle is this?
Answer:
The steps of construction are as follows.
(i) Draw a line segment QR of length 3.5 cm.
(ii) Taking point Q as centre, draw an arc of 4 cm radius.
(iii) Taking point R as centre, draw an arc of 4 cm radius to intersect the previous arc at point P.
(iv) Join P to Q and R.
ΔPQR is the required triangle. As the two sides of this triangle are of the same length (PQ = PR), therefore, ΔPQR is an isosceles triangle.
Question 4:
Construct ΔABC such that AB = 2.5 cm, BC = 6 cm and AC = 6.5 cm. Measure ∠B.
Answer:
The steps of construction are as follows.
(i) Draw a line segment BC of length 6 cm.
(ii) Taking point C as centre, draw an arc of 6.5 cm radius.
(iii) Taking point B as centre, draw an arc of radius 2.5 cm to meet the previous arc at point A.
(iv) Join A to B and C.
ΔABC is the required triangle. ∠B can be measured with the help of protractor. It comes to 90º.
