The two angles formed by the intersection of two straight lines are related as 4: 5 find all four corners.

1. Let’s denote one part by x.

2. Define the degree measure of angle 1:

5 * x = 5x.

3. Find out the degree measure of angle 2:

4 * x = 4x.

4. The sum of adjacent angles is equal to 180˚, we compose and solve the equation:

5x + 4x = 180˚;

9x = 180˚;

x = 180˚: 9;

x = 20˚.

5. One part is equal to x = 20˚.

6. What is angle 1?

5 * 20˚ = 100˚.

7. What is the degree measure of angle 2?

4 * 20˚ = 80˚.

8. Since at the intersection of two straight lines two pairs of vertical angles are formed, and as you know, the vertical angles are equal, then angle 1 = angle 3 = 100˚, angle 2 = angle 4 = 80˚.

Answer: 100˚, 80˚, 100˚, 80˚.