If the sum of two angles is $90^\circ$ then, it is called Complementary Angles. In a right-angled triangle, one angle is $90^\circ$ , so the sum of the other two angles is also $90^\circ$ or they are complementary angles.so the trigonometric ratios of the complementary angles will be –

Sin $(90^\circ - A)$ = cos A,

cos $(90^\circ - A)$ = sin A,

Tan $(90^\circ - A)$ = cot A,

Cot $(90^\circ - A)$ = tan A,

Sec $(90^\circ - A)$ = cosec A,

Cosec $(90^\circ - A)$ = sec A

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