Question

If sin = 1/2, then find the value of 3 cos - 4 cos ³ THETA

Answer 1

Answer:

sin A= 1/2

$sin ^2 + cos^2 = 1$

sin^2A + cos^2A=1

cos^2A= 1-sin^2A

cos^2A = 1-(1/2)^

cos^2A = 1- 1/4

cos^2A = 3/4

cos A = Root3 /2

Now

3cosA - 4Cos ^3A

3*root3/2-4(root3/2)^3

3root3/2- 4*3root3/8

3root3/2-3root3/2

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Answer 2

Answer:

sin Ф = 1/2

sin Ф= sin 30°

Ф= 30°

so                                              

3cosФ - 4cos^3Ф                  or cos3Ф=cos 90=0

3cos30° - 4cos^3 30°

$3( \sqrt{3} /2) - 4( \sqrt{3} /2)^{3} = 0$

Step-by-step explanation: