Question

y= asinA, x=acosA is the euation of a circle or not if yes then why?,

Answer 1

see the general equation of the circle can be (x-h)^2+(y-k)^2=a^2
where (h, k) are the coordinates of the center and a is the radius
so if we square the values you have given oh x and y then we get
x^2+y^2=(asinA)^2+(acosA)^2
x^2+y^2=a^2 (sinA^2+cosA^2)
and as we know sinA^2+cosA^2 will be 1 then we get finally
x^2+y^2=a^2
which we can say is a eq of circle with center (0, 0) and radius, a