Question

cos2u=cos^2u-sin^2u

Answer 1

hi

Answer 2

wait y did you delete it

Answer 3

thanks

Answer 4

wait wait i think i did some wrong calculations wait !

Answer 5

omg lol

Answer 6

@antoni7 wont it rather be
\[\cos 2u=\cos ^{2}u-(1-\cos ^{2}u)\]

Answer 7

\[\cos 2u=\cos ^{2}u-1+\cos ^{2}u\]