Answer:
First triangle: 54.46 degrees
Explanation:
For the first problem, solve for the third side, then the third angle, and then subtract from 180.
20^2 + 28^2 = c^2
400 + 784 = c^2
1184 = c^2
34.41 = third side
Find the third angle:
sin(90)/34.41 = sin(x)/20
20 * sin(90)/34.41 = sin(x)
35.54 is the third angle.
180 - 35.54 - 90 = 54.46. The angle with the question mark is 54.46. Do the other 2 problems the same way.