Question

EXERCISE 8.2 1. ABCD is a quadrilateral m which RQ. R and Sare mid-points of the sides AB, BC, CD and DA (see Fig 8.29). AC is a diagonal. Show that​

Answer 1

Step-by-step explanation:

We will use the mid-point theorem here. It that states that the line segment joining the mid-points of any two sides of the triangle is parallel to the third side and is half of it. 

(i) In ΔADC, S and R are the mid-points of sides AD and CD respectively. Thus, by using the mid-point theorem

∴ SR || AC and SR = 1/2AC ... (1)

(ii) In ΔABC, P and Q are mid-points of sides AB and BC. Therefore, by using the mid-point theorem,

PQ || AC and PQ = 1/2 AC ... (2)

Using Equations (1) and (2), we obtain PQ || SR and PQ = SR ... (3)

∴ PQ = SR

(iii) From Equation (3), we obtained PQ || SR and PQ = SR

Clearly, one pair of opposite sides of quadrilateral PQRS is parallel and equal. Hence, PQRS is a parallelogram.