Question

if sin a=1/2 and a is an acute angle find the value of (3cosa-4cos^3a)

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Answer 1

Answer:

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Step-by-step explanation:

hope this helps

Answer 2

Answer:

0

Step-by-step explanation:

*copy my steps in your notebook then it will be easy to understand for you*

sin a = 1/2

=> sin a = sin 30°

=> a = 30°

3 cos a - 4 cos^3 a

= 3 * (3^-2)/2 - 4 * {(3^-2)/2}^3

= 3 * (3^-2)/2 - 4 * 3 * (3^-2)/8

= [4 * 3 * (3^-2) - 4 * 3 * (3^-2)] / 8

= 0 / 8

= 0