In a triangle, the measure of the first angle is twice the measure of the second angle. The measure of the third angle is 80° more than the measure of the second angle. Use the fact that the sum of the measures of the three angles of a triangle is 180° to find the measure of each angle. what is the measure of the first angle?

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xKelvin xKelvin · Answer 1 · 2021-06-25T19:39:16+02:00

Answer:

The measure of the first angle is 50°.

Step-by-step explanation:

Let the three angles be a, b, and c.

The measure of the first angle is twice the measure of the second angle. In other words:

[tex]a=2b[/tex]

The measure of the third angle is 80° more than the measure of the second angle. In other words:

[tex]c=b+80[/tex]

And since the interior angles of a triangle must equal 180°:

[tex]a+b+c=180[/tex]

Substitute a and c:

[tex](2b)+b+(b+80)=180[/tex]

Combine like terms:

[tex]4b+80=180[/tex]

Subtract 80 from both sides:

[tex]4b=100[/tex]

And divide both sides by four:

[tex]b=25^\circ[/tex]

So, the measure of the second angle is 25°.

Since the measure of the first is twice the second, the measure of the first angle is 50°.

(And since the measure of the third is 80° than the second, the measure of the third angle is 105°.)