Interpretation of complementary angle: the sum of two angles is equal to a right angle (90? ), these two angles complement each other. For example, two acute angles of a right triangle are complementary angles.

If ∠ A+∠ C = 90, there are:

∠A = 90°-∠C，∠C = 90°-∠A，

So the complementary angle of ∠A = 90-∠ A, and the complementary angle of ∠C = 90-∠ C.

Remarks: The two complementary angles in mathematics are acute angles, not right angles, obtuse angles and right angles. Complementary angle cannot appear alone. We can only say that Angle A and Angle B are complementary angles or that Angle A is complementary angle of Angle B, but we can't say that Angle A is complementary angle.

Extended data:

1, congruence angles of the same angle or the same angle are equal.

If ∠ A+∠A+∠B = 90°, ∠A =∠D+∠ C = 90, ∠ A = ∠ D.

Then there is ∠ c = ∠ B. That is, the complementary angles of equal angles are equal.

2. The conclusion of trigonometric function about complementary angle:

If ∠ A+∠A+∠B = 90°, there are sinA=cosB and cosA = sinB；; tanA×tanB= 1 .

If there is an angle ∠ α, then ∠βand ∠αhave the following relationship: ∠β+∠α = 90.

And there is a ∠ γ, which makes ∠βhave the following relationship with it: ∠β+∠γ = 180.

Then we can say that γ is the complementary angle of α.

If the sum of two angles is a right angle, then these two angles are called complementary angles; If the sum of two angles is a right angle, then these two angles are called complementary angles.

The complementary angle (complementary angle) of the same angle (equal angle) is equal.

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