Question

Is it possible for a triangle PST to have ∠S = ∠T = 90°?​

Answer 1

We know that the sum of the angles in a triangle of 180°
So, ∠P + ∠S + ∠T = 180
But, if ∠S = ∠T  = 90
Then
∠P + 90 + 90 = 180
∠P + 180 = 180
∠P = 180 - 180
∠P = 0

As we know, we cannot have a triangle with only 2 angles, so it is IMPOSSIBLE for △PST to have ∠S = ∠T = 90°