Math, asked by aryansh8948, 11 months ago

If cosx= -2/5, then the value of cos3x is

Answers

Answered by Kpv5348

8

Step-by-step explanation:

formula cos3x =4cos^3x-3cosx

cos3x=4(-2/5)^3-3×(-2/5)

= -32/125+2/5

= -32+50/125

=18/125

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