Using the Graphing Calculator with Degrees, Radians and Trig Angle Entries

Degrees, Radians, and Trig Angle Entries

Remember: The calculator defaults to Radian measure.

Working with Degrees:

There are two ways to engage "Degrees" when working with the calculator:
             1. Set the MODE to Degree and all further calculations will be in degrees.
          2. If in Radian MODE, use the Degree Symbol (2nd APPS (Angle) and select #1 º ).
               The degree status will be applied to that one calculation only. All other calculations
                will return to radian mode.

Converting Degrees to Radians:

Find the radian measure of an angle whose measure is 500º.

Method 1: (in Radian or Degree mode) Convert by multiplying by .	Mode set to Radian
Method 2: (in Radian mode) With the mode set to Radian, type 500º. Notice the degree symbol. Hit Enter.

NOTE: If in Degree mode, you can force an answer to radians by using
2^nd APPS(Angle) #3 r.

In Degree mode,	but ......
gives the answer 0.0548036651 (WRONG!!!)	gives the correct answer of 0.

Converting Radians to Degrees:

Find the degree measure of an angle whose measure is .

Method 1: (in Radian or Degree mode) Convert by multiplying by .	Mode set to Degree
Method 2: (in Degree mode) In Degree mode, the r symbol can be used to convert radians to degrees. The r is found 2^nd APPS(Angle) #3 r. With the mode set to Degree, type

Convert 57º 45' 17'' to decimal degrees:

In either Radian or Degree Mode: Type 57º 45' 17'' and hit Enter.
       º is under Angle (above APPS) #1
        ' is under Angle (above APPS) #2
        '' use ALPHA (green) key with the quote symbol above the + sign.
                                                                                                     Answer: 57.75472222

Convert 57º 45' 17'' to radians:

With the mode set to Radian: Type 57º 45' 17'' º and hit Enter.
** Note the use of the additional degree symbol at the end. Without it, conversion would be to decimal degrees, even though the mode is set to radians.

Convert 48.555º to degrees, minutes, seconds:

Type 48.555 ►DMS Answer: 48º 33' 18''
The ►DMS is #4 on the Angle menu (2^nd APPS). This function works even if Mode is set to Radian.

Given cos A = .0258. Find <A expressed in degree, minutes, seconds.

With the mode set to Degree: Type cos^-1(.0258). Hit Enter.
Engage ►DMS Answer: 88º 31' 17.777''
(Be careful here to be in the correct mode!!)

Find sin 57º 45' 17'':

Enter sin(57º 45' 17'' º). This problem is clearly dealing with degrees. The entry shown here works even if MODE is set to Radian. Answer: .8457717984
If MODE is set to Degree, the degree symbol at the end is not needed.

Find cos(-250º 21'):

Enter cos (-250º 21' º) when in Radian mode. Answer: -.3362735421
If MODE is set to Degree, the degree symbol at the end is not needed.

Find sec(25º 40'):

There is no key for secant. But, since , enter: 1/cos(25º 40' º) when in Radian mode. If MODE is set to Degree, the degree symbol at the end is not needed.
Answer: 1.109472591

Find :

Enter directly: when in Radian mode. Answer: -.7660444431
If in Degree mode, enter .

Find :

There is no key for cosecant. But, since , enter: when in Radian mode. Answer: 1.015426612

In Degree mode, enter .

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