Question

lowing
(cos 20 + i sin 20
(cos 40 + i sin 46​

Answer 1

Answer:

We have, cos20−sin20=p ...(1)

Squaring equation (1) we get,

cos

2

20+sin

2

20−2sin20cos20=p

2

1+sin(2×20)=p

2

⇒sin40=1−p

2

{∵2sinθcosθ=sin2θ}

cos40=

1−sin

2

40

⇒cos40=

1−(1−p

2

)

2

=p

2−p

2

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