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Cos(−θ)=√3/4 , sinθ<0

What is the value of sinθ ?

2 Answers

1 vote

Answer:

  • as written, sin(θ) = -√13/4
  • perhaps, sin(θ) = -1/2

Two answers are given because the question is "unexpected." cos(θ) = √(3/4) is more commonly seen in such problems than is cos(θ) = (√3)/4, which is what you have written here. Choose the answer that matches your intent.

Explanation:

The cosine function is an even function, so cos(θ) = cos(-θ).

The relationship between sin(θ) and cos(θ) is ...

... sin(θ) = ±√(1 -cos(θ)^2)

For sin(θ) < 0 and cos(θ) = (√3)/4, ...

... sin(θ) = -√(1 -3/16) = -√(13/16)

... sin(θ) = -(√13)/4

For sin(θ) < 0 and cos(0) = √(3/4), ...

... sin(θ) = -√(1 -3/4) = -√(1/4)

... sin(θ) = -1/2

User Axay Prajapati
by
6.1k points
0 votes

Answer:

-√13/4 took the test.

User Hasanaga
by
6.6k points