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Complementary Angle Calculator

Find the angle that adds to 90 degrees

Complementary Angle Formula

complement = 90° - θ

Complementary angles are two angles whose sum is 90 degrees. This calculator subtracts the given angle from 90 degrees to find its complement.

Enter an angle from 0° to 90°. Larger angles do not have a standard nonnegative complement.

How Complementary Angles Work

In a right angle, the two acute parts add to 90 degrees. Complementary angles also connect to cofunction identities such as sin θ = cos(90°-θ).

Right Angle

Complementary angles total 90°.

Input Angle

Must be between 0° and 90°.

Complement

Found by subtracting from 90°.

Cofunctions

Complements connect sine and cosine.

💡 Example: For 35°, the complementary angle is 90°-35°=55°.

Applications of Complementary Angles

Right TrianglesCofunction IdentitiesGeometry ProofsAngle Problems

Frequently Asked Questions

What is a complementary angle calculator?
It finds the angle that adds with the input angle to make 90 degrees.
What is the complementary angle formula?
Complement = 90° - angle.
How do I use this calculator?
Enter an angle from 0° to 90° and click Calculate.
Can an obtuse angle have a complement?
No. Standard complementary angles are nonnegative angles that add to 90°.
Where are complementary angles used?
They are used in right triangles, cofunction identities, geometry proofs, and angle problems.

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