Big Ideas Math: Modeling Real Life, Grade 8
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2. Angles of Triangles
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Exercise 13 Page 115

The sum of the measures of the interior angles of a triangle is 180^(∘).

44^(∘), 48^(∘), and 88^(∘)

Practice makes perfect

We want to find the measures of the angles in the given triangle.

A triangle with interior angle measures of 48 degrees, x degrees, and (x-44) degrees
To find these angle measures, we will first recall a key piece of information!

Angle Sum of a Triangle

The sum of the measures of the interior angles of a triangle is 180^(∘).

With this rule, we can write an equation connecting the measures of the angles of our triangle. x^(∘)+ (x-44)^(∘)+ 48^(∘)=180^(∘) Let's solve the equation and find the value of x. For simplicity, we will not write the degree symbol.
x+(x-44)+48=180
Solve for x
x+x-44+48=180
2x+4=180
2x=176
x=88
The measure of one of the angles is 88^(∘). To find the other missing measure, we will substitute x= 88 in the expression for the remaining angle, (x-44)^(∘). Once again, we will remove the degree symbol for the calculation.
x-44
88-44
44
The measure of the third angle is 44^(∘).
triangle