First, figure out the measurement of angle 2. Take 180 degrees (the total of the triangle) and subtract 90 (the right angle) and 53 (the given measurement of angle 1). 180-90-53=37
Angle 2 measures 37 degrees. The measurements of angles 2 and 3 need to equal 180 when added together as they form a straight line, so take the total (180) and subtract the value of angle 2 (37). 180-37=143
