Holly G.

asked • 07/22/21

Find the exact value of each trigonometric ratio.

a) cos30°

b) sin225°

1 Expert Answer


Holly G.

what are the steps to get a?


Jacob C.

Consider an equilateral triangle with each side of length 6. Each angle will be 60 degrees because it is equilateral. If we draw a line from a corner of the triangle to the midpoint of the opposing line, we will form a 30, 60, 90 triangle with one side length 6/2 = 3 and the hypotenuse 6. It’s straightforward to show, using the Pythagorean Theorem, that the remaining side length is 3sqrt(3). Thus, the cosine of the 30 degree angle is 3sqrt(3)/6 = sqrt(3)/2.


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