How do you prove #cos2x=1-2sin^2x# using other trigonometric identities?
1 Answer
Mar 1, 2016
see explanation
Explanation:
Using
#color(blue)" Double angle formula "#
#• cos2x = cos^2 x - sin^2 x# and the identity
# cos^2x = 1 - sin^2x #
#rArrcos2x = cos^2x - sin^2x = (1-sin^2x) - sin^2x #
# = 1 - 2sin^2x = " right hand side "# hence proved.
