Topic explanation

Standard explanation

r = sqrt(x²+y²). tan theta = yx, then pick the quadrant from the signs of x and y. Do not blindly take tan^-1(yx) if x < 0.

Key points

• quadrant first
• r = |z|
• z = r (cos theta + i sin theta)
• quadrant
• FIND R AND THETA: r = sqrt(x^2+y^2). tan theta = yx, then pick the quadrant from the signs of x and y. Do not blindly
• FIND r AND theta: r = sqrt(x²+y²).
• WHAT — FIND R AND THETA: r = sqrt(x^2+y^2). tan theta = yx, then pick the quadrant from the signs of x and y. Do not blindly
• WHY — Why it matters: This rule is a separate learning unit inside argand plane and polar form. It can be defined, applied

Labelled diagram