Class notes Mathematics

Class 10
Maths
Chapter 8 (Introduction to Trigonometry)

1. Trigonometric Ratios (Right-Angled Triangle ke liye)

ΔABC me, ∠B = 90°,

 sin A = Opposite / Hypotenuse = BC/AC
 cos A = Adjacent / Hypotenuse = AB/AC
 tan A = Opposite / Adjacent = BC/AB
 cosec A = Hypotenuse / Opposite = AC/BC
 sec A = Hypotenuse / Adjacent = AC/AB
 cot A = Adjacent / Opposite = AB/BC


2. Ratio Relationships

 cosec A = 1/sin A, sec A = 1/cos A
 tan A = sin A / cos A, cot A = cos A / sin A



3. Common Trigonometric Identities

 sin²A + cos²A = 1
 1 + tan²A = sec²A
 1 + cot²A = cosec²A



4. Specific Angle Values (0°, 30°, 45°, 60°, 90°)

θ sin θ cos θ tan θ cosec θ sec θ cot θ
0° 0 1 0 undefined 1 undefined
30° 1/2 √3/2 1/√3 2 2/√3 √3
45° 1/√2 1/√2 1 √2 √2 1
60° √3/2 1/2 √3 2/√3 2 1/√3