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If cosx=-0.25, then cos(pi-x)=...

If `cosx=-0.25`, then cos`(pi-x)`=

A

`-0.25`

B

`-0.75`

C

0

D

0.25

Text Solution

Verified by Experts

The correct Answer is:
D
If cos x is negative, then x must be in QII or QIII. Iff x is in QII, then -x is in QIII, so `pi-x` is QI. If x is in QIII, then -x is in QII, so `pi-x` is in QIV. Therefore, `cos(pi-x)=0.25`. You could also key in `cos^(-1)(-0.25)` and then key in `cos(pi-Ans)` to get 0.25.
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