If the coordinates of the mid points of the sides PQ and QR of ΔPQR are (-1, 8) and (2, 4) respectively, then length of PR is :
Answer & explanation
Correct answer: option 2
Let us consider that mid point of PQ is X and mid point of QR is Y.
Length of PR = 2 × length of XY
Length of XY = \(\sqrt { ( x2 - x1 )² + ( y2 - y1 )² }\)
= \(\sqrt { ( 2 -(-1) )² + ( 4 - 8 )² }\)
= \(\sqrt { 9 + 16 }\)
= \(\sqrt { 25 }\) 5
So, length of PR = 2 × 5 = 10
The correct answer is option (2) : 10