Question

show that (1) cos 36 degree cos 54degree -sin 36 degree sin 54degree= 0​

Answer 1

Step-by-step explanation:

cos36cos54-sin36sin54

this is formula basic

so we can write

cos(36+54)

cos(90)

0

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Answer 2

given : cos 36 cos 54 - sin 36 sin 54=0

LHS= cos 36 cos54 - sin36sin 54

cos 36 cos(90 - 54) -sin36 sin(90-54)

cos 36 sin 36 - sin36 - cos 36

=0

hence proved

hope it helps you......