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If sin 3A =cos(A-10^(@)) where 3A is an ...

If `sin 3A =cos(A-10^(@))` where 3A is an acute angle , then find the value of A.

A

`35^(@)`

B

`25^(@)`

C

`20^(@)`

D

`45^(@)`

Text Solution

Verified by Experts

The correct Answer is:
B
`sin 3A=cos(A-10^(@))rArr cos(90^(@)-3A)=cos(A-10^(@))`
`rArr 90^(@)-3A=A-10^(@)rArr 4A=100^(@)rArr A =25^(@).`
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