Microsoft Office Tutorials and References

In Depth Information

**Getting an Angle on Trigonometry**

If the angles are in degrees, then they need to be converted into radians by

using the RADIANS function. In this case you would use these:

=SIN(RADIANS(angle))

=COS(RADIANS(angle))

=TAN(RADIANS(angle))

Which leads us to…

Degrees and radians

An angle can be expressed in degrees or radians. A degree is more common

to us non–rocket scientists. Most everyone know that there are 360 degrees

in a circle, or that a right angle is 90 degrees, or even that doing a “180”

means turning completely around and going the other way.

One radian = 180/pi degrees, and one degree = pi/180 radians. All this

talk about pi is making me hungry! For lowdown and quick conversion:

1 radian = 57.3 degrees.

Pi is approximately equal to 3.14159. See the beginning of this chapter for a

forkful of pi.

Excel provides the RADIANS and DEGREES functions to convert a number

from radians to degrees or vice versa. I think the real reason they did this

was to keep pi out of the picture so we would concentrate on work and not

dessert.

The functions are the single argument type:

=RADIANS(angle in degrees)

=DEGREES(angle in radians)

Using some numbers, we can see that 90 degrees = 1.5707963267949 radians

and so 1.5707963267949 radians must equal 90 degrees. And it does.