Given:
The right angled triangle is shown in the figure attached.

Required:
To find the measure of

Step-by-step explanation:
From the figure provided, we see that

and

are supplementary angles.
Therefore, the sum of measures of angles is 180.
Thus,

Since the triangle is right angled triangle, one of the angles of a triangle is of measure

We know that the sum of measures of angles of a triangle is

Hence, the measure of angle 3 is given by,

Final Answer: