



 
Nazrul, One way to approach this problem is to use sin^{2}A = 1  cos^{2}A and hence write
Square both sides and solve the resulting equation for cosA. Select the solutions for which 0 ≤ A ≤ 90^{o} and verify that any solutions actually satisfy the original equation. Harley  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 