Question

simplify cos100.cos40+sin100.sin40​

Answer 1

Answer:

Step-by-step explanation:

First take the L.H.S

cos 100 .cos40 + sin 100.sin40

Here we use the formula,

cos (a-b) = cos a cos b + sin a sin b

Then L.H.S becomes,

cos (100–40) = cos 60 = 1/2 = R.H.S (proved)

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