How do you find a measure of an angle

it really depends on what shape you're measuring but you commonly measure it with a protractor, there are online ones if you don't have one on you.

To find the measure of the smallest angle of the triangle, we multiply 4 times 10. So, 4 x 10 = 40. Remember, the sum of the angles of a triangle is 180 degrees. Just take what you are given in a problem and try to determine what will make the final angle add up to 180 degrees.