If im given cos81 = 0.1564, how do i evaluate other cosines without a calculator? Like cos99 and cos279 for example.

As property of trigonometry:

cos x = - cos(180 - x)

=> cos 99 = - cos(180 - 99) = - cos 81 = - 0.1564

cos x = cos(360 - x)

=> cos 279 = cos(360 - 279) = cos 81 = 0.1564

Hope this helps!

:)

step-by-step explanation:

so first find out how much each is worth.

quarter= 25 cents

dime= 10 cents

pennies= 1 cent

then multiply each by how much each is worth.

200                     150                   300

x                         x                     x   1

  25                       10              

                                  300

1000                     1500

+                          

4000                                      

5000                                  

then count 2 from the back and add a period.

$50.00

$15.00

$3.00

and then add them

  $50.00

+

  $15.00

+

    $3.00

$68.00

so sunghee has $68.00

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the answer is b.

step-by-step explanation:

by the trigonometric ratio tangent, tangent equals opposite divided by adjacent.

therefore, tan(50) equals ac/3

multiply each side by 3 to get: ac=3tan(50)

the answer is b.