Answer:
[tex] \displaystyle \angle3 = {90}^{ \circ} [/tex]
Step-by-step explanation:
we are given two angles
we are want to figure out the missing angle
remember,
Straight line theorem
so we acquire
[tex] \displaystyle \angle3 + \angle4 = {180}^{ \circ} [/tex]
substitute the value of the given angle:
[tex] \displaystyle \angle3 + {90}^{ \circ} = {180}^{ \circ} [/tex]
cancel 90° from both sides:
[tex] \displaystyle \angle3 = {90}^{ \circ} [/tex]
hence, the measure of the missing angle is 90°
