Answer:
∠1 = 36°
Explanation:
The triangle in the image is a right triangle.
The sum of interior angles in a triangle is equal to 180° and one of the angles is given as 54° while the other would be 90° since this is a right triangle.
90 + 54 + ∠1 = 180 add like terms
144 + ∠1 = 180 subtract 144 from both sides
∠1 = 36°