Question

Form adjoining figure calculate area of triangle BCD

Answer 1

Heya user,

Applying pythagoras in ΔABD,
AD = $\sqrt{41^2 - 40^2^2}$ = $\sqrt{81}$ = 9;

Hence, [ ABD ] = 1/2 * 40 * 9 = 9 * 20 = 180 cm²
---------> [ ABCD ] = 1/2 [ 40 + 15 ] * 9 = 1/2 * 55 * 9 = 495/2 = 247.5 cm²

Therefore, [ BCD ] = [ABCD] - [ ABD ] = 247.5 - 180 = 67.5 cm²