Question

Given that sin^-1(sina+sinb)+sin^-1(sina-sinb)=90,find the value of sin^2 a+sin^2 b.

Answer 1

hi, do you know some inverse triginometirc relations ?
like
90 - sin^-1 A = cos^-1 A

and
cos^-1 A = sin^-1 (sqrt(1-A^2))
heard of them ?
you'll need them for this question

Answer 2

but there's no cosine in my equation

Answer 3

but we can have '90 - sin^-1 A' form and get cosine....
if you don't have and need the list of inverse trigonometric formulae, you can look here,
http://en.wikipedia.org/wiki/Inverse_trigonometric_functions

Answer 4

sin^-1(sina+sinb)+sin^-1(sina-sinb)=90
sin^-1(sina+sinb)=90- sin^-1(sina-sinb)

Answer 5

sin^-1(sina+sinb)= cos^-1(sina-sinb)
makes sense ?

Answer 6

yup, thanks, i see,
i need to shift it to the right hand side,thanks

Answer 7

welcome ^_^
try to solve it further, if you get stuck, i'm always there :)

Answer 8

'kay,thanks again