Answer:
∠ 1 = 123°
Explanation:
One way
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ 1 is an external angle of the triangle, thus
∠ 1 = 90° + 33° = 123°
Second way
The sum of the 3 angles in a triangle = 180°
Subtract the sum of the 2 given angles from 180 for third angle in Δ
third angle = 180° - (90 + 33)° = 180° - 123° = 57°
The third angle and ∠ 1 form a straight angle and are supplementary, thus
∠ 1 = 180° - 57° = 123°