question_answer

Find the perimeter of the rectangle whose length is 40 cm and a diagonal is 41 cm.

Answer:

Let ABCD be a rectangle such that AB = 40 cm and AC = 41 cm. In right angled ΔABC, right angled at B, by Pythagoras theorem, we have     x\[={{41}^{2}}{{40}^{2}}\]   = (41 + 40) (41 ? 40)   = 81 × 1 = 81   \[BC=\sqrt{81}=9cm,\]             Now, perimeter of rectangle   = 2(AB + BC)   = 2(40 + 9) cm   =2 × 49 cm = 98 cm