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Complementary angles facts for kids

Kids Encyclopedia Facts

Complementary angles are two angles that add up to exactly 90 degrees. Think of it like a perfect corner or a quarter turn. When you put these two angles together, they form a right angle.

What Are Complementary Angles?

When two angles combine to make a 90-degree angle, they are called complementary. Each angle is the "complement" of the other. For example, if you have an angle that is 30 degrees, its complementary angle would be 60 degrees. This is because 30 + 60 equals 90.

Finding a Complementary Angle

It's easy to find the complementary angle if you know one of them. You just subtract the known angle from 90 degrees.

  • If Angle A is 40 degrees, its complement is 90 - 40 = 50 degrees.
  • If Angle B is 75 degrees, its complement is 90 - 75 = 15 degrees.

This simple math helps us understand how angles relate to each other.

Where Do We See Them?

Complementary angles are important in many areas, especially in geometry and construction.

  • In Triangles: In a right triangle, the two angles that are not the right angle are always complementary. They always add up to 90 degrees.
  • In Architecture: Architects and builders use these angle relationships to make sure buildings are stable. They need to create perfect corners.
  • In Sports: Even in sports like basketball or pool, understanding angles can help you aim better.

Examples of Complementary Angles

Here are some pairs of angles that are complementary:

  • 10 degrees and 80 degrees
  • 25 degrees and 65 degrees
  • 45 degrees and 45 degrees (two equal angles can be complementary!)
  • 5 degrees and 85 degrees

Complementary vs. Supplementary Angles

It's good to know the difference between complementary and supplementary angles.

  • Complementary angles add up to 90 degrees.
  • Supplementary angles add up to 180 degrees (a straight line).

Remembering "C" for corner (90 degrees) and "S" for straight (180 degrees) can help you keep them apart.

Images for kids

  • Two rays and one vertex

    An angle formed by two rays emanating from a vertex.

See also

Kids robot.svg In Spanish: Ángulos complementarios para niños

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Complementary angles Facts for Kids. Kiddle Encyclopedia.