Question

value of 8 cos^3 - 6 cos^ 10​

Answer 1

Step-by-step explanation:

2cos10 (4cos^2 10 - 3)

2cos10 ( 4 - 4 sin^2 10 - 3)

2cos10 (1-4sin^2 10)

2cos10 (cos ^2 10 - 3sin^2 10)

2cos10 (cos 20 - 2sin^2 10)

2cos10 (cos 20 +cos20 - 1)

2cos10 (2cos20 - 1)