The sine of 30 degrees in 1/2.............or 0.5....................same thing.......................the cosine of 60 degrees in 1/2................the length of a right triangle...........whose two lesser sides are both one......hence a 45/45 degree triangle...........is the square root of 2..........................1/2 the square root of 3 is the sine of 60 degrees...............the square root of 2 added to the square root of 3.........is a close approx. to pi.....................

The student should sketch the triangle and place the ratio numbers. Since the cosine is the ratio of the adjacent side to the hypotenuse, you can see that cos 60° = ½. Example 2.   Evaluate sin 30°. Answer.   According to the property of cofunctions (Topic 3), sin 30° is equal to cos 60°.   sin 30° = ½. You can see that directly in the figure above. Problem 1.   Evaluate sin 60° and tan 60°. To see the answer, pass your mouse over the colored area. To cover the answer again, click "Refresh" ("Reload"). The sine is the ratio of the opposite side to the hypotenuse.     sin 60° =   2  = ½. Lesson 5 of Algebra. The tangent is ratio of the opposite side to the adjacent.     tan 60° =   1 =