Question

In a given right triangle, If 0 º < x < 90 º and cos x = √ 3 / 2, then sin x = ?

Answer 1

Answer:

  1/2

Step-by-step explanation:

The "Pythagorean relation" between trig functions can be used to find the sine.

Pythagorean relation

The relation between sine and cosine is the identity ...

  sin(x)² +cos(x)² = 1

This can be solved for sin(x) in terms of cos(x):

  sin(x) = √(1 -cos(x)²)

Application

For the present case, using the given cosine value, we find ...

  sin(x) = √(1 -(√3/2)²) = √(1 -3/4) = √(1/4)

  sin(x) = 1/2

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Additional comment

The sine and cosine of an angle are the y and x coordinates (respectively) of the corresponding point on the unit circle. The right triangle with these legs will satisfy the Pythagorean theorem with ...

  sin(x)² + cos(x)² = 1 . . . . . . where 1 is the hypotenuse (radius of unit circle)

A calculator can always be used to verify the result.