The adjacent sides of a parallelogram are 21 cm and 28 cm. If its one diagonal is 35 cm; find the area of the parallelogram.
Answers:
First we find area of ABC.
Sides are, a = 28 cm
b = 35 cm
and c = 21 cm
S = (a + b + c)/2
= (28 + 35 + 21)/2
= 84/2 = 42 cm
= 2 × 21 × 7
= 294 cm2
∵ Diagonal of ∥ gm divides it into two equal parts.
∴ area of ∥ gm = 2 × area of ∆ ABC
= 2 × 294
= 588 cm2