IXL | Find missing angles in triangles using ratios

One angle of a triangle measures 15°. The other two angles are in a ratio of 4:7. What are the measures of those two angles?

° and °

ref_doc_title.

Learn with an example

question

One angle of a triangle measures 50°. The other two angles are in a ratio of 6:7. What are the measures of those two angles?

° and °

key idea

The measures of the angles of a triangle add up to 180°.

solution

Since the angles are in a ratio of 6:7, they have measures of 6n and 7n. Set the sum of the angle measures equal to 180° and solve.

50° + 6n + 7n

180°

Combine like terms

50° + 13n

180°

Combine like terms

Subtract 50° from both sides

13n

180° − 50°

Subtract 50° from both sides

Simplify

13n

130°

Simplify

Divide both sides by 13

10°

Divide both sides by 13

Now plug in n = 10° to find the measures of the angles.

6n and 7n

6 × 10° and 7 × 10°

60° and 70°

So, the measures of the two angles are 60° and 70°.

Looking for more? Try these:

Lesson: Interior angles of triangles

Lesson: Ratios

Lesson: Solving equations

$Confetti$

Excellent!

Now entering the Challenge Zone—are you ready?

Questions
answeredQuestions

Time
elapsedTime

hr	min	sec
00	00	04

SmartScore
out of 100
IXL's SmartScore is a dynamic measure of progress towards mastery, rather than a percentage grade. It tracks your skill level as you tackle progressively more difficult questions. Consistently answer questions correctly to reach excellence (90), or conquer the Challenge Zone to achieve mastery (100)! Learn more

Teacher tools

Work it out

Not feeling ready yet? These can help:

Q.7Find missing angles in triangles

M.11Solve equations involving like terms

Lesson: Interior angles of triangles

Lesson: Ratios

Lesson: Solving equations

Excellent! You got that right!

Jumping to level 1 of 1

Excellent!