Answer:
x = 8 cm
Explanation:
The first step in solving this problem is to determine which trig function applies. The diagram shows that this triangle is a right triangle, that side x is opposite the 25-degree angle, and that the hypotenuse has a length of 18 cm.
The sine function of an angle Ф is defined as the ratio of the opposite side to the hypotenuse. In this case, sin Ф (or sin 25 degrees) equals x/(18 cm).
We need to determine the value of x. Adapt the above equation to this particular situation: sin 25 degrees = x/(18 cm).
To solve for x, multiply both sides of the most recent equation, above, by (18 cm). The following results: (18 cm)(sin 25 degrees) = x.
Next, use a calculator to find the value of sin 25 degrees: It is 0.4226.
Then the desired value of x is (18 cm)(0.4226), or x = 7.61 cm. This should be rounded off to x = 8 cm to reflect the level of accuracy of the given 18 cm.