Q7 If tan (A + B) = √3 and tan (A – B) = 1 and A, B (B < A) are acute angles, find the values of A and B.
Solution :
Q8 Without using trigonometrical tables, evaluate the following:
(i) sin2 28° + sin2 62° – tan2 45°
(ii)
(iii) cos 18° sin 72° + sin 18° cos 72°
(iv) 5 sin 50° sec 40° – 3 cos 59° cosec 31°
Solution :
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Q9 Prove that:
Solution :
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Q10 When 0° < A < 90°, solve the following equations:
(i) sin 3A=cos 2A (ii) tan 5A=cot A
Solution :
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Q11 Find the value of θ if
(i) sin (θ + 36°) = cos θ, where θ and θ + 36° are acute angles. (ii) sec 4θ = cosec (θ – 20°), where 4θ and θ – 20° are acute angles.
Solution :
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Q12 In the adjoining figure, ABC is right-angled triangle at B and ABD is right angled triangle at A. If BD ⊥ AC and BC = 2√3cm, find the length of AD.