Question

What is cos 30?

Answer 1

@pooja195

Answer 2

\[\dfrac{\sqrt{3}}{2}\]

Answer 3

you can get that by taking

\[\large \boxed{\cos \theta =\dfrac{\text{adjacent side}}{hypotenuse}}\]

Answer 4

cos(x) = (adjacent)/(hypotenuse)

Answer 5

o find the trig functions of 30-60-90 degrees, you can figure it out easily rather than memorizing and forgetting.

Draw an equilateral triangle, and label each side 2.

Cut it in half, bisecting a 60-degree angle and forming a right angle at the base. You're actually drawing the altitude of the equilateral triangle.

Now you have two 30-60-90 right triangles, so just work with one. The hypotenuse, which was a side of the equilateral, is 2, and the side that was halved is 1. Great, now you've got two sides of a right triangle and can easily use the Pythag. Thm. to find the third (which is the altitude of the equilateral triangle).

You also know that the angle that was halved is your 30. Now you've got all three angles, all three sides, and can use SOH, CAH, TOA for your 30 and 60.

For the 90, you'll need to go to the unit circle. 90 degrees is at the top of the y-axis on the unit circle. The coordinates there are (0,1) GREAT! y is sine ("why sign") and x is cosine, so, again it's easy to see.

Answer 6

http://answers.yahoo.com/question/index?qid=20071217045254AA6KVns

Answer 7

@pooja195 its better posting the link rather than giving the copied version here

Answer 8

arg