Verified answer

In Euler's formula, the function cis(θ) = cos θ + i·sin θ = ₑiθ.

9 cis 60° / 8 cis 90°

= (9/8)[cis 60° / cis 90°]

= (9/8) (ₑi 60° / ₑi 90°)

= (9/8) ₑi (60°-90°)

= (9/8) ₑi (-30°)

= (9/8) ₑi (360°-30°)

= (9/8) ₑi(330) same as (9/8) cis 330°

{60° & 90° should be converted to Radians as π/6, π/4, but fortunately no damge was done here}

Cis 90