Trigonometry
-
If tan θ = 1, then the value of 8sin θ + 5cos θ is sin3θ - 2cos3θ + 7cos θ
-
View Hint View Answer Discuss in Forum
tanθ = 1
⇒ θ = 45°∴ 8 sin θ + 5 cos θ sin3θ - 2cos3θ + 7 cosθ
Correct Option: A
tanθ = 1
⇒ θ = 45°∴ 8 sin θ + 5 cos θ sin3θ - 2cos3θ + 7 cosθ
-
If tan θ = 1, then the value of 8sin θ + 5cos θ is sin3θ - 2cos3θ + 7cos θ
-
View Hint View Answer Discuss in Forum
tanθ = 1
⇒ θ = 45°∴ 8 sin θ + 5 cos θ sin3θ - 2cos3θ + 7 cosθ
Correct Option: A
tanθ = 1
⇒ θ = 45°∴ 8 sin θ + 5 cos θ sin3θ - 2cos3θ + 7 cosθ
- If sin α sec (30° + α) = 1 (0 < a < 60°), then the value of sin α + cos 2α is
-
View Hint View Answer Discuss in Forum
sinα = 1 cos(30° + α) ⇒ sinα = 1 sin(90° - 30 - α) ⇒ sinα = 1 sin(60° - α)
⇒ sin α = sin (60° – α)
⇒ 2α = 60° ⇒ α = 30°
∴ sinα + cos 2α
= sin 30° + cos 60°= 1 + 1 = 1 2 2
Correct Option: A
sinα = 1 cos(30° + α) ⇒ sinα = 1 sin(90° - 30 - α) ⇒ sinα = 1 sin(60° - α)
⇒ sin α = sin (60° – α)
⇒ 2α = 60° ⇒ α = 30°
∴ sinα + cos 2α
= sin 30° + cos 60°= 1 + 1 = 1 2 2
- If cos4 θ – sin4 θ = (2 / 3) , then the value of 2 cos²θ– 1 is
-
View Hint View Answer Discuss in Forum
cos4 θ - sin4 θ = 2 3 (cos2 θ + sin2 θ) (cos2 θ – sin2 θ) 2 3 ⇒ cos2 θ - sin2 θ 2 3 ⇒ 2cos2 θ - 1 2 3
Correct Option: C
cos4 θ - sin4 θ = 2 3 (cos2 θ + sin2 θ) (cos2 θ – sin2 θ) 2 3 ⇒ cos2 θ - sin2 θ 2 3 ⇒ 2cos2 θ - 1 2 3
- If sin α + cos β = 2 (0° ≤ β ≤ α ≤ 90°), then sin (2α + β / 3) =
-
View Hint View Answer Discuss in Forum
sinα + cosβ = 2
sinα ≤ 1 ; cosβ ≤ 1
⇒ α = 90° ; β = 0°= sin 60° = √3 2
Also,cos α = cos 30° = √3 3 2
Correct Option: B
sinα + cosβ = 2
sinα ≤ 1 ; cosβ ≤ 1
⇒ α = 90° ; β = 0°= sin 60° = √3 2
Also,cos α = cos 30° = √3 3 2