Question

The length of two adjacent sides of a parallelogram are 40 cm 50 cm one of its diagonal is 20 centimetre find area of parallelogram

Answer 1

Area of parallelogram = 40*50cm2 = 2000cm2

Answer 2

Let the two adjacent sides of the parallelogram be a = 51 cm, b = 37 cm Let the length of diagonal be c = 20 cm These two sides and the diagonal forms a triangle semi perimeter, s = (a + b + c) / 2 s = (51 + 37 + 20)/2 = 54 cm By Heron's formula, we have area of triangle, Δ = √s(s - a)(s - b)(s - c) = √[54(54 - 51)(54 - 37)(54 - 20) = √54 x 3 x 17 x 34 = 306 sq cm Area of parallelogram = 2 x area of triangle = 2 x 306 = 612