" 9."(1)/(1+cos x)

Evaluate : lim_(x rarr0)(27^(x)-9^(x)-3^(x)+1)/(1-cos x)

lim_(x rarr 0) (1-cos 7x)/(1- cos 9x) =

int(1)/(9+cos x)dx

int(1)/(9+16cos^(2)x)dx

y = (27 ^ (sin x) * 81 ^ (1 + cos x)) ^ ((1) / (9)) has

tan [(pi) / (4) + (1) / (2) (cos ^ (- 1)) (9) / (6)] + tan [(pi) / (4) - (1) / (2 ) (cos ^ (- 1)) (9) / (6)] =

Find the value of sin ^(-1)(sin""(5x)/(9) cos""(pi)/(9)+cos""(5x)/(9)sin""(x)/(9))

Prove that (1+cos pi/9) (1 + cos 3pi/9) (1+ cos 5pi/9) (1 + cos 7pi/9) =9/16 .

" (9) "int( sin2 x)/(1+cos^(2)x)dx