If sin = 1/2then show that 3cos - 4cos^3=0

Step-by-step explanation:

sen (x) = 0.5

3cos (x) - 4cos^3 (x) = 0

Remember:

cos^3 (x) = cos (x) * cos^2 (x)

3cos (x) - 4 (cos (x) * cos^2 (x)) = 0

we have:

cos^2 (x) = 1-sin^2 (x)

Then:

3cos (x) - 4 (cos (x) * (1-sin^2 (x))) = 0

sin^2 (x) = (0.5) ^2=0.25

3cos (x) - 4 (cos (x) * (1-0.25)) = 0

3cos (x) - 4 (cos (x) * (0.75)) = 0

Finally

3cos (x) - 3cos (x) = 0