📚 Topic Summary
Complementary angles are two angles that add up to 90 degrees. Think of a right angle being split into two smaller angles. To find a missing complementary angle, simply subtract the known angle from 90 degrees. This worksheet will give you practice identifying and calculating complementary angles, helping you build a solid understanding of this key geometry concept.
📐 Part A: Vocabulary
Match the term to its definition:
| Term |
Definition |
| 1. Complementary Angles |
A. An angle measuring 90 degrees |
| 2. Right Angle |
B. Two angles that add up to 90 degrees |
| 3. Acute Angle |
C. An angle measuring less than 90 degrees |
| 4. Obtuse Angle |
D. An angle measuring greater than 90 degrees but less than 180 degrees |
| 5. Angle |
E. The space between two intersecting lines or surfaces at or close to the point where they meet. |
Match the following: 1-B, 2-A, 3-C, 4-D, 5-E
✍️ Part B: Fill in the Blanks
Two angles are said to be __________ if their sum is 90 degrees. If one angle measures 35 degrees, then its complement measures __________ degrees. To find a missing complementary angle, we __________ the given angle from 90 degrees. Complementary angles always form a __________ angle when combined. An example of complementary angles would be 60 degrees and __________ degrees.
Answer Key: complementary, 55, subtract, right, 30
🤔 Part C: Critical Thinking
Can two obtuse angles be complementary? Explain your reasoning.
Answer: No, two obtuse angles cannot be complementary. An obtuse angle is greater than 90 degrees. If you add two angles that are each greater than 90 degrees, their sum will always be greater than 180 degrees, and therefore they cannot add to 90 degrees.