Something like TRIGONOMETRY?

Question

If xSin^3A + yCos^3A = SinA and xSinA - yCosA = 0,
Prove that:
x^2 +y^2 =1

Answer 1

Recheck the question. It should have been
xSin³A + yCos³A = SinA Cos A

and usp, 1+tan²A = sec²A, not 1.

Answer 2

multiply the second eqn by cos^2A & add it with the first

you wil get

xsin^3A + xsinA cos^2A = sinA

sinA(x) = sin A ( since sin^2A + cos^2A =1)

x=1

putting it in second eqn

y= sinA/cosA =tanA

thus
x^2+y^2 = 1+tan^2A =1 (identity)

Answer 3

it is very difficult for i studied very less hope you find answer here