Question

For finding modulus of a complex number , can we use the formula r=root(x^2+y^2) instead of r(cosA + sin A) = z . In the examination? Will marks be deducted?

Answer 1

Actually, complex number is expressed in cartesian form as well as polar form.
Cartesian form, z = x + iy
Polar form , z = r (cosA + sin A)

And modulus will be,
IzI = √(x²+y²)
or IzI = √[(rcosA)² + (rsinA)²]
         = r²