In the following practice questions, you're asked to combine this property of supplementary angles with some algebra to get your answers.
Practice questions
- In the drawing, l1 is parallel to l2. What is the value of a? A. 60 degrees B. 70 degrees C. 80 degrees D. 90 degrees
- In the following image, the angles are supplementary. What is the value of k? A. 17 B. 18 C. 19 D. 20
Answers and explanations
- The correct answer is Choice (D). If l1 is parallel to l2, all the acute angles are equivalent and all the obtuse angles are equivalent. This makes the angles marked a + b and a – b supplementary, meaning they total 180 degrees. Set up the equation and solve for a:
- The correct answer is Choice (C). Supplementary angles total 180 degrees. Add the angles and set them equal to 180: