The trigonometric function defined as the ratio of the adjacent side to the hypotenuse in a right triangle is called what?

The trigonometric function defined as the ratio of the adjacent side to the hypotenuse in a right triangle is called what?

• A. Sine
• B. Cosine
• C. Tangent
• D. Secant

Answer: (B)

In a right triangle, trigonometric functions describe how the sides relate to a given acute angle. The cosine of that angle is defined as the ratio of the length of the adjacent side to the hypotenuse. In other words, the side that touches the angle (the one next to it) divided by the hypotenuse gives the cosine. For example, in a 3-4-5 triangle, take the angle opposite the side of length 3. The adjacent leg is 4 and the hypotenuse is 5, so the cosine is 4/5 = 0.8. That shows why the ratio adjacent over hypotenuse matches cosine. The other options correspond to different ratios: sine is opposite over hypotenuse, tangent is opposite over adjacent, and secant is hypotenuse over adjacent.

In a right triangle, trigonometric functions describe how the sides relate to a given acute angle. The cosine of that angle is defined as the ratio of the length of the adjacent side to the hypotenuse. In other words, the side that touches the angle (the one next to it) divided by the hypotenuse gives the cosine.

For example, in a 3-4-5 triangle, take the angle opposite the side of length 3. The adjacent leg is 4 and the hypotenuse is 5, so the cosine is 4/5 = 0.8. That shows why the ratio adjacent over hypotenuse matches cosine.

The other options correspond to different ratios: sine is opposite over hypotenuse, tangent is opposite over adjacent, and secant is hypotenuse over adjacent.