How do you use a calculator to evaluate cos(-110^circ)?

Mar 1, 2018

See below

Explanation:

To find it using calculator just do the simple steps below:
¤click on cos
¤then type -110

How to calculate it yourself.

$\implies$ $\cos \left(- \theta\right) = \cos \theta$

cos (-110°)=cos110°

cos (-110°)=-cos70°=-sin20°

Either simply calculate this by calculator or use a bunch of identities to solve.

Using calculator is a good way but if you are practicing math try making cubic or quartic polynomials also which you can solve using wolframalpha.

Mar 1, 2018

See below...

Explanation:

For this explanation i will be using the regular casio scientific calculator...

First select your "cos" button on the calculator...

Then input $- {110}^{\circ}$ by pressing "-" then "110" on the keypad

Now we must close the bracket that has already been opened when we first pressed "cos", press the bracket ")"

Then press the "ans" button to give the answer, that will be displayed on the display..

You should get $- 0.34202 \ldots$

$\implies \cos \left(- {110}^{\circ}\right) = - 0.342$ to 3 decimal places

If you get something different, follow the procedure to get your calc in "degrees" mode

shift $\to$ mode $\to$ 3:Deg