Question

what type of special triangle is this?

Explanation:

Step1: Identify given angles

One angle is 90° and another is 45°.

Step2: Calculate third - angle

Using the angle - sum property of a triangle ($180^{\circ}$ in a triangle), the third angle is $180-(90 + 45)=45^{\circ}$.

Step3: Determine triangle type

Since two angles are equal (both 45°) and one is 90°, it is a 45 - 45 - 90 special right - triangle. Also, a triangle with two equal angles is isosceles, but the more specific special - triangle name here is 45 - 45 - 90.

Answer:

C. 45°-45°-90°