IXL - Identify complementary, supplementary, vertical, adjacent, and congruent angles (Geometry practice)

Which angle is complementary to 3?

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question

Which angle is complementary to 2?

key idea

Complementary angles have measures that add to 90°.

Vertical angles are angles formed opposite each other when two lines intersect. Vertical angles are congruent.

solution

Look at 2 and 4:

4 is complementary to 2. First, notice that 2 and 1 are complementary. Along with the right angle, they form a straight line. The straight line measures 180° and the right angle measures 90°. That leaves another 90°, so 2 and 1 have measures that add up to 90°. Next, notice that 1 and 4 are vertical angles. That means they have the same measure. Since 2 and 1 are complementary, 2 and 4 are also complementary. Their angles add up to 90°.

Looking for more? Try these:

Lesson: Complementary angles

Lesson: Supplementary angles

Lesson: Vertical angles

Lesson: Adjacent angles

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