Question

What type of triangle is shown?

A. Equiangular triangle

B. Acute triangle

C. Right triangle

D. Obtuse triangle

I can safely eliminate option A. and B. I just need help deciding if it is a right triangle, or obtuse.

Answer 1

C

Explanation:

4x-10+2x+15+x=180

7x+5=180

7x=175

x=25

So 2x+15=65 and 4x-10=90.

90+65+25=180

So your triangle is a right triangle.

Answer 2

C

Explanation:

A triangle is 180 degrees. This means all the sides added up will be 180 degrees, so what you need to do is turn it into an algebra problem.

x + 4x + 15 + 2x - 10 = 180

Simplify.

7x + 5 = 180

Subtract 5 from both sides.

7x = 175

Divide by 7.

x = 25

4(25) - 10 = 20

This is a right angle, which means that C is the correct answer.