Question

If xcosA – ysinA = 0 and xsinA + ycosA = b, then,
(A) x^2 – y^2 = a^2 – b^2
(B) a^2 + y^2 = a^2 + b^2
(C) x^2 + y^2 = a^2 – b^2
(D) x^2 – y^2 = a^2 + b^2

Answer 1

Step-by-step explanation:

Square both the equations and add them

X^2cos^2A+Y^2sin^2A-2XYcosAsinA+X^2sin^2A+

Y^2cos^A+2XYsinAcosA= a^2+b^2

But cos^2A+sin^2A=1

So we get x^2+Y^2=a^2+b^2