Mathematics, Uncategorized

Introduction to Trigonometry-Exercise 8.3-Class 10

1. Evaluate (i) sin18˚/cos72˚ (ii) tan26˚/cot64˚ (iii) cos48˚ - sin42˚ (iv) cosec31˚ - sec59˚ Solution: (i) sin18˚/cos72˚ = [sin(90˚-72˚)]/cos72˚ = cos72˚)]/cos72˚ =1   (ii) tan26˚/cos64˚ = tan(90˚-64˚)/cos64˚ = cot64˚/cot64˚ = 1   (III) cos 48° − sin 42° = cos (90°− 42°) − sin 42° = sin 42° − sin 42° = 0   (iv) cosec… Continue reading Introduction to Trigonometry-Exercise 8.3-Class 10

Mathematics, Uncategorized

Introduction to Trigonometry-Exercise 8.2-Class 10

Evaluate the following (i) sin60° cos30° + sin30° cos 60° (ii) 2tan2 45° + cos2 30° − sin2 60° (iii)  (cos45°)/(sec30°+cosec30°) (iv) (v) Solution: (i) sin60° cos30° + sin30° cos 60° =  √3/2   x  √3/2 +  1/2  x ½ = 3/4 + 1/4 = 4/4 = 1   (ii) 2tan2 45° + cos2 30° − sin2 60° =… Continue reading Introduction to Trigonometry-Exercise 8.2-Class 10

Mathematics, Uncategorized

Introduction to Trigonometry-Exercise 8.1-Class 10

1. In ∆ABC right angled at B, AB = 24 cm, BC = 7 m. Determine (i) sin A, cos A (ii) sin C, cos C  Solution: (i) Applying Pythagoras theorem for ∆ABC, we obtain AC2 = AB2 + BC2 = (24 cm)2 + (7 cm)2 = (576 + 49) cm2 = 625 cm2 ∴ AC… Continue reading Introduction to Trigonometry-Exercise 8.1-Class 10