Question

the adjacent sides of 11 gm 34 cm and 20 cm, diagonal 42 cm. Find area.

Answer 1

ABCD is a parallelogram and
In Triangle ABC
AB= 34 cm , BC = 20 cm and CA=42 cm
$S = \frac{a+b+c}{2} = \frac{34 + 20 + 42}{2} = \frac{96}{2} = 48 \: cm \\ Area \: of \: triangle = \sqrt{s(s - a)(s - b)(s - c)} \\ = \sqrt{48(48 - 34)(48 - 20)(48 - 42)} \\ = \sqrt{48 \times 14 \times 28 \times 6} \\ = 336cm ^{2} \\ Area \: of \: parallelogram = 2×336 = 672 \: {cm}^{2}$