Sin, Cos, Tan with a calculator

If you are finding the sin, cos, tan of an angle that is not a special case (30, 60, 45) you can use your calculator to approximate its value to 4 decimal places

Make sure your calculator is in the proper mode (degrees or radian) based on the problem you are solving

There is a sin, cos, tan button on your calculator – you hit that button and then put the angle your are working with in parenthesis

Sin, Cos, Tan with a calculator

If you are working with Radians make sure that you use the button Always round to 4 decimal places if it is not an exact answer

Your calculator will find the sin, cos, tan of any angle – however if it is a special case angle (30, 60, 45) your are expected to use your chart to put down the EXACT answer (Fraction)

Examples

Find the sin 65º

Make sure your calculator is in degrees (hit the mode button – then the 3rd selection down is radian or degrees, highlight the one you want and hit enter, then hit 2nd mode to go back to the main screen)Hit the sin button and then 65 to get:sin(65) = .906307787 (round to 4 decimals)

sin(65) = .9063 (rounded)

Examples

Find the tan

Make sure your calculator is in radiansHit the tan button and then (2 /7) to get:tan(2 /7) = 1.253960338 (round to 4 decimals)

tan(2 /7) = 1.2540 (rounded)

2

7

Remember that to get the you hit 2nd and then the ^ key

Inverse Trig FunctionsIf we start out with the trig value we can find the angle that it comes from by using the inverse trig functions

For the special angles (30, 60, 45) you can use the charts, for all other angles we will use the calculatorYou will see these written two different ways:Our book uses arcsin, arccos, arctan – your calculator uses the following: 1sin

1cos 1tan

Inverse Trig FunctionsIf you see something written as arcsin(.2345) it is asking you to find the angle that has a sin value of .2345

For something like that (arcsin(.2345)) we will use the calculator

If we are asked something like arcsin(1/2) we need to use the chart

When to use the chartsIf you see the following look at your charts to get the angles:

1

23

22

2

3

33 12 3

3The only decimal you will use the chart for is .5 which is equal to 1

2

Examples

Find the arctan for an angle in both radians and degrees

You use the chart because this is one of the special angles

Looking in the degree chart you can see that 30º has this value for its tan

Looking in the radian charts you can see that has this value for its tan

6

3

3

Examples

Find the arcsin(.75) in degrees and radians

Hit 2nd sin on your calculator to get arcsin or so you can get an angle – you will need to do this in both radians and degrees

1sin

1sin (.75) 48.590

1sin (.75) .848 Radians