Question

WILL REWARD THE BRAINLIEST

Answer 1

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!

Answer 2

Answer:

9-18

a)

x = 180 - (115 + 30) = 180 - 145 = 35°

b)

3x = 180 => x = 180 : 3 => x = 60°

9-19

a)

180 = x + 2x + 30

180 - 30 = 3x

3x = 150

x = 50°

b)

180 = x + 10 + x + 90

180 - 10 - 90 = 2x

2x = 80

x = 40°