Find the values of x and y.

Question image

Understand the Problem

The question is asking to find the values of x and y in a right triangle where one angle is 30 degrees and the opposite side is 9. It involves applying trigonometric principles to solve for the unknown sides.

Answer

$x = \frac{9\sqrt{3}}{2}, \; y = 18$
Answer for screen readers

The values are ( x = \frac{9\sqrt{3}}{2} ) and ( y = 18 ).

Steps to Solve

  1. Identify the triangle properties

The triangle is a right triangle with one angle measuring $30^\circ$. The side opposite the $30^\circ$ angle is given as $9$.

  1. Using the sine function for side ( y )

In a right triangle, the sine of an angle is the ratio of the length of the opposite side to the hypotenuse. We can use: $$ \sin(30^\circ) = \frac{\text{opposite}}{\text{hypotenuse}} $$ Thus, $$ \sin(30^\circ) = \frac{9}{y} $$

Since ( \sin(30^\circ) = \frac{1}{2} ), we have: $$ \frac{1}{2} = \frac{9}{y} $$

  1. Solve for ( y )

Multiply both sides by ( y ) and then by ( 2 ): $$ y = 18 $$

  1. Using the cosine function for side ( x )

Now we can use the cosine function for the angle to find side ( x ): $$ \cos(30^\circ) = \frac{\text{adjacent}}{\text{hypotenuse}} $$ This translates to: $$ \cos(30^\circ) = \frac{x}{9} $$

  1. Solve for ( x )

Since ( \cos(30^\circ) = \frac{\sqrt{3}}{2} ), we have: $$ \frac{\sqrt{3}}{2} = \frac{x}{9} $$

Multiply both sides by ( 9 ): $$ x = 9 \cdot \frac{\sqrt{3}}{2} $$ Thus, $$ x = \frac{9\sqrt{3}}{2} $$

The values are ( x = \frac{9\sqrt{3}}{2} ) and ( y = 18 ).

More Information

In a 30-60-90 triangle, the ratios of the lengths of the sides are ( 1 : \sqrt{3} : 2 ). This means that the side opposite the ( 30^\circ ) angle is half the length of the hypotenuse.

Tips

  • Misapplying the sine or cosine functions by not correctly identifying the opposite and adjacent sides relative to the given angle.
  • Forgetting to use the correct ratios for a 30-60-90 triangle can lead to incorrect side lengths.

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