Question

Integral problem

Answer 1

have you tried
x= sin y /9
??

Answer 2

dx = ...?
numerator= sin^8 y / 9^8

denominator = 9^11 cos^11 y

then try to bring in terms of tan y and sec y

Answer 3

let me know if you get stuck again

Answer 4

next substitution would be t = tan y

Answer 5

ooh okay, i only know of
x = a*sin
x = a*tan
x = a*sec
substitutions

Answer 6

now try with the substitution i proposed.
x = (1/9) sin y
and see whether you can solve it further

Answer 7

okay let me see

Answer 8

i just realised, x = 9 sin y will actually work in thiscase
81 - x^2 = 81- 9^2 sin^2 y = 81 (1-sin^2 y) = 81 cos^2 y