Question

Find the area of PAROLLOGRAM whose adjustent side are in 5cm7cm and diognal is 8cm

Answer 1

Answer:

20√3 cm²

Explanation:

using cosine law

8² = 7² + 5² + 70cos∝ , cos ∝ = - 1/7

sin∝ = 4√3/7

area = 2 (1/2) (35)(4√3/7) =    20√3 cm²

Answer 2

Explanation:

So, in triangle ABC:

AB = 5cm

BC = 7cm

CA = 8cm.

$\sqrt{s(s - a)(s - b)(s - c)}$

Total perimeter is =5 + 7 + 8.

............................ 20cm.

semi perimeter = 20/2.

S = 10cm.

so, according to formula;

$\sqrt{10(10 - 7)(10 - 5)(10 - 8)}$

$\sqrt{10 \times 3 \times 5 \times 2}$

by splitting above root we get,

$\sqrt{2 \times 5 \times 3 \times 5 \times 2}$

we get,

$2 \times 5 \sqrt{3}$

$10 \sqrt{3} cm {}^{2}$

multiply whole by 2 because there is two similar triangle in above parallelogram.

$2 \times 10 \sqrt{3}$

we recieve;

$20 \sqrt{3} cm {}^{2}$

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