Geometry question about a octagonal

Question

PQRSTUVZ is a regular octagonal. Find angle RZS. I found that the mass of all anglrs is 1080° and each angle is 135°. Now, I don't know hoe to find that one.

Answer 1

Draw and label a diagram!

ZPQR is an isosceles trapezoid.

m∠PZR = m∠QRZ, Of course ∠P = ∠Q

Use this and the sum of the four being 360º to determine m∠PZR and m∠QRZ.

STUVZ has three angles of 135°. And m∠ZST = m∠SZV. .

Use this and the sum of the 5 angles being 540º to determine m∠ZST and m∠SZV.

From here you can determine m∠RZS.