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SAI International School
CLASS - X
Mathematics
CHAPTER-8: Introduction to Trigonometry
Lesson Notes- 3
SUBTOPIC :TrigonometicRatios of Complementary Angles
Trigonometric Ratios of Complementary Angles
If the sum of two angles is 90° then, they are called Complementary Angles. In a right-
angled triangle, one angle is 90 °, so the sum of the other two angles is also 90° or they
are complementary angles.
In triangle ABC, ∠B = 90 °
So, ∠A + ∠C = 90 °
∠A &∠C are complementary angles.
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