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# Important definitions and formulas - Introduction to Trigonometry Class 10 Notes | EduRev

## Class 10 : Important definitions and formulas - Introduction to Trigonometry Class 10 Notes | EduRev

The document Important definitions and formulas - Introduction to Trigonometry Class 10 Notes | EduRev is a part of the Class 10 Course Mathematics (Maths) Class 10.
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Definitions and Formulas

• An angle is positive if it is measured in the anticlockwise direction and negative if it is measured in the clockwise direction.
• In a right triangle ABC, right-angled at B  Reciprocal Relations • If one of the trigonometric ratios of an acute angle is known, the remaining trigonometric ratios can be determined.
• Two angles are said to be complementary if their sum is 90°, and each one of them is called the complement of the other.
sin (90° - θ) = cos θ
cos (90° - θ) = sin θ
tan (90° - θ) = cot θ
cot (90° - θ) = tan θ
sec (90° - θ) = cosec θ
cosec (90° - θ) = sec θ
Trigonometric Identities

An equation with trigonometric ratios of an angle θ, which is true for all values of ‘θ’, for which the given trigonometric ratios are defined, is called an identity.
Three fundamental trigonometric identities are
(a) sin2θ + cos2θ = 1
(b) sec2θ = 1 + tan2θ
(c) cosec2θ = 1 + cot2θ

Table: Values of trigonometric ratios of 0°, 30°, 45°, 60° and 90° Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

## Mathematics (Maths) Class 10

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