The measures of the angles in a triangle are in the ratio 2:2:5. To find the actual angle measures, an equation is set up where the sum of the angles equals 180 degrees. The equation 9x=180 is solved to get x=20. Then x=20 is substituted back into the original ratio to determine the three angle measures are 100 degrees, 40 degrees, and 40 degrees.

1. Triangle Ratio Example

2. The measures of the angles in a triangle are in
the extended ratio of 2:2:5. Find the measures
of the angles.
• Draw a Picture, label the angles
5x
2x 2x

3. Set up your equation
• The angles in a triangle always add to 180 so:
2x +2x + 5x = 180

4. Solve
• 2x +2x +5x =180
• 9x=180
• x=20

5. Substitute
• The problem wants the angles, not x. Plug in x=20 into your angles.
5x=5(20)=100
2x=2(20)=40 2x=2(20)=40

6. Answer
• Your angle measures are 100°, 40°, and 40°