Properties of Special Triangles:

Calculate the size of angle AEF

90 degrees

Step-by-step explanation:

The angle of AEF is 90°.

Step-by-step explanation:

Given that DEF is an equilateral triangle so all angles are the same which is 60° and in a regular square, all angles are 90°. Next, we have to find ∠ADE :

∠EDF = 60° / ∠CDF = 180° / ∠CDA = 90°

∠ADE = 180° - ∠EDF∠CDA

∠ADE = 180° - 60° - 90°

∠ADE = 30°

Given that ADE is an isosceles triangle so ∠ADE and ∠AED have the same angles. Lastly, we have to find ∠AEF by adding ∠AED and ∠DEF together :

∠AED = 30° / ∠DEF = 60°

∠AEF = ∠AED + ∠DEF

∠AEF = 30° + 60°

∠AEF = 90°