WILL REWARD THE BRAINLIEST

9-18
Use what you have learned about triangles and angles to write an equation that represents each situation. Then find each of the missing angles in the triangles below.
9-19.
Additional Challenge: Use what you know about triangles and angle relationships to find the missing angles in the triangles below.

Answers and Step-by-step explanations:

9-18.

a) All the angles of a triangle add up to 180, by definition. So, we can write the expression: 30 + 115 + x = 180.

Then, we can just solve for x by subtracting 30 and 115 from both sides:

x = 180 - 115 - 30 = 35 degrees

b) Again all three angles should add up to 180, so:

x + x + x = 180  ⇒  3x = 180  ⇒  x = 180/3 = 60 degrees

9-19.

a) These angles add up to 180:

2x + x + 30 = 180  ⇒  3x + 30 = 180  ⇒  3x = 150  ⇒  x = 50

2x = 50 * 2 = 100

The missing angles are 100 degrees and 50 degrees.

b) Again, these add up to 180:

x + 10 + x + 90 = 180  ⇒  2x + 100 = 180  ⇒  2x = 80  ⇒  x = 40

x + 10 = 40 + 10 = 50

The missing angles are 50 degrees and 40 degrees.

Hope this helps!

practice. practice. practice.