How this calculator works
Complements divide a right angle. The two angles can be separate in a drawing; only their measures need to sum to 90 degrees. Choose find to subtract one angle from the target sum, or check to test two measures. Nonnegative angles through the target are accepted, including a zero angle at the boundary. Comparisons allow a tolerance of 10^-10 radians to absorb unit conversion rounding.
Formula
For complementary angles, alpha + beta = 90 degrees. Therefore beta = 90 degrees - alpha.
Worked example
A 30 degree angle has a 60 degree complement. Two angles of 45 degrees are also complementary.
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Frequently asked questions
Can I enter radians?
Yes. The target sum is pi/2 radians, and every supported unit converts before the calculation.
What if my angle is too large?
An angle greater than 90 degrees has no nonnegative complementary partner in this calculator. An inline error asks for a measure in range.
Are zero angles allowed?
Yes. The boundary pair is 0 degrees and 90 degrees. Some classes restrict the term to positive angles; follow that convention if required.