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If cosecθ + cotθ = 11 and θ is acute, then cosθ equals:

Competition practiceTrigonometry
  • A11/61
  • B60/61
  • C61/60
  • D1/11

Step-by-Step Solution

Since coseθ − coθ = 1, the two expressions are reciprocals, so cosecθ − cotθ = 1/11. Adding gives 2cosecθ = 11 + 1/11 = 122/11, so cosecθ = 61/11 and sinθ = 11/61; subtracting gives 2cotθ = 11 − 1/11 = 120/11, so cotθ = 60/11. The right triangle is therefore 11, 60, 61 (and ), giving cosθ = 60/61 ≈ 0.9836, with θ ≈ 10.4° — a small angle, as an 11 in the sum demands. The near misses are the other ratios of that same triangle: 11/61 is sinθ and 61/60 is secθ, while 1/11 is just the conjugate expression cosecθ − cotθ.
Answer: B) 60/61

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