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Trignometry 1. The value of cos …

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Trignometry 1. The value of cos 0°. cos 1°. cos 2°. cos 3°… cos 89° cos 90° is (a) 1 (b) -1 (c) 0 (d) 12√ 2. If x tan 45° sin 30° = cos 30° tan 30°, then x is equal to (a) √3 (b) 12 (c) 12√ (d) 1 3. If x and y are complementary angles, then (a) sin x = sin y (b) tan x = tan y (c) cos x = cos y (d) sec x = cosec y 4. sin 2B = 2 sin B is true when B is equal to (a) 90° (b) 60° (c) 30° (d) 0° 5.If A and (2A – 45°) are acute angles such that sin A = cos (2A – 45°), then tan A is equal to (a) 0 (b) 13√ (c) 1 (d) √3 6. If y sin 45° cos 45° = tan2 45° – cos2 30°, then y = … (a) –12 (b) 12 (c) -2 (d) 2 7. If sin θ + sin² θ = 1, then cos² θ + cos4 θ = .. (a) -1 (b) 0 (c) 1 (d) 2 8. 5 tan² A – 5 sec² A + 1 is equal to (a) 6 (6) -5 (c) 1 (d) -4 9. If x = a cos 0 and y = b sin 0, then b2x2 + a2y2 = (a) ab (b) b² + a² (c) a²b² (d) a4b4 10. What is the maximum value of 1cscA? (a) 0 (b) 1 (c) 12 (d) 2 11. What is the minimum value of sin A, 0 ≤ A ≤ 90° (a) -1 (b) 0 (c) 1 (d) 12 12. What is the minimum value of cos θ, 0 ≤ θ ≤ 90° (a) -1 (b) 0 (c) 1 (d) 12 13. If cos 9A = sin A and 9A < 90°, then the value of tan 5A is (a) 0 (b) 1 (c) 13√ (d) √3 14. If in ΔABC, ∠C = 90°, then sin (A + B) = (a) 0 (b) 1/2 (c) 12√ (d) 1 15. If sin A – cos A = 0, then the value of sin4 A + cos4 A is (a) 2 (b) 1 (c) 34 (d) 12
  • 1 answers

Gaurav Seth 2 years, 7 months ago

1.  Answer = 0

Step-by-step explanation:

the value of the series cos0°.cos1°.cos2°.cos3°.......cos89°.cos90° is '0' because the value of cos90° is 0 so,hence the value of the series is 0.

 

2. 

Answer: x = 1

 

Step-by-step explanation:

xtan45sin30 = cos30(sin30/cos30)

x(1)(1/2) = sin30

x/2 = 1/2

x = 1

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