Question

Justin was asked to write equations based on the triangle below. So far he has come up with the following equations: Which of the following would be another correct equation?

Answer 1

C: tan 60 = √3

Explanation:

Let the adjacent part of the triangle be x and let the opposite side be y.

Thus, from trigonometric ratios;

x/10 = cos 60

We are given cos 60 = ½

Thus;

x/10 = ½

x = ½ × 10

x = 5

Similarly;

y/10 = sin 60

Now,from trigonometric relationship we know that; sin 60 = cos 30. Thus;

y/10 = cos 30

We are given cos 30 = (√3)/2

Thus;

y/10 = (√3)/2

y = 10 × (√3)/2

y = 5√3

Since it is a right angle triangle with one angle being 60°, it means the other one is 30° since sum of angles in a triangle is 180°.

Thus;

5/(5√3) = tan 30°

1/√3 = tan 30

Similarly;

5/10 = sin 60°

sin 60° = ½

Also;

tan 60 = (5√3)/5

tan 60 = √3

Also;

sin 30 = 5/10

sin 30 = ½

Looking at the options, the only correct one is Option C