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 ° ).
               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 500°.

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 500°. 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 57° 45' 17'' to decimal degrees:

In either Radian or Degree Mode: Type 57° 45' 17'' and hit Enter.
       ° 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 57° 45' 17'' to radians:

With the mode set to Radian: Type 57° 45' 17'' ° 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 48.555° to degrees, minutes, seconds:

Type 48.555 ►DMS Answer: 48° 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: 88° 31' 17.777''
(Be careful here to be in the correct mode!!)

Find sin 57° 45' 17'':

Enter sin(57° 45' 17'' °). 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(-250° 21'):

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

Find sec(25° 40'):

There is no key for secant. But, since , enter: 1/cos(25° 40' °) 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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