4. Find m_1.
140°
650

∠ 1 = 50°

Step-by-step explanation:

The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.

140° is an exterior angle of the triangle, thus

90° + ∠ 1 = 140° ( subtract 90° from both sides )

∠ 1 = 50°

50 degrees

Step-by-step explanation:

To find the measure of angle 1, you must first find the other unknown angle in the triangle. You can find this through supplementary angles. The bottom angle as well as 140 must be equal to 180 because they are supplementary, so to find it solve 180-140, which is 40. Now two of the angles in the triangle are known, one is 40 and the other is 90 as shown by the square. You know that every angle equals 180 degrees, so to find angle 1 add the known angles and subtract that from 180. 180-(90+40), which equals 50. So m<1=50.

step-by-step explanation: