Chapter 12.1, Problem 18E

To determine

To Calculate: The supplementary angle of a given angle.

Answer to Problem 18E

The measure of the angle that forms a straight angle when placed adjacent to an angle measuring ${124}^o$ is ${56}^o$ .

Explanation of Solution

Given Information: Two angles form a straight angle when placed adjacent to each other and one of the angles measures ${124}^o$ .

  

Concept Used: If two angles placed adjacent to each other form a straight angle, the angles are called supplementary angles and the sum of their measures is ${180}^o$ .

Calculation: Write the sum of the measures of the angles as being equal to ${180}^o$ .

  $m\angle 1+{124}^o={180}^o$

  $\Rightarrow m\angle 1={180}^o-{124}^o={56}^o$$$

Therefore, the measure of the angle that forms a straight angle when placed adjacent to an angle measuring ${124}^o$ is $56^o$ .