Question

Cos54°cos36°-sin54°sin36°=0 prove that using trigonometric tables

Answer 1

$\text{Class 10 solution:}\\\cos54\cos36-\sin54\sin36\\=\sin{(90-54)}\sin{(90-36)}-\sin54\sin36\\=\sin36\sin54-\sin54\sin36\\=0\\\text{Class 11 solution:}\\\cos54\cos36-\sin54\sin36\\=\cos{(54+36)}=\cos90=0\\ \text{(Proved using trig table seeing value of cos 90)}$

Answer 2

Answer:

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Step-by-step explanation:

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