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If sec 4A="cosec"(A-10^(@))and 4A" is a...

If `sec 4A="cosec"(A-10^(@))and 4A" is acute then " angle A=?`

A

`20^(@)`

B

`30^(@)`

C

`40^(@)`

D

`50^(@)`

Text Solution

Verified by Experts

The correct Answer is:
A
`sec4A="cosec"(A-10^(@))rArr"cosec"(90^(@)-4A)="cosec"(A-10^(@))`
`rArr 90^(@)-4A=A-10^(@)rArr 5A=100^(@) rArr A =20^(@).`
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RS AGGARWAL-TRIGONOMETRIC IDENTITIES-Multiple Choice Questions (Mcq)
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