81. cos θ x r

82. Solve for the x vector.

The function formula to use is:

Unknown isolated:

x = cos θ x r

x = _______

82.

x = 76.6

83.

You have used only three trig function formulas, even though

the various symbols might cause you to think differently. The

symbols used depend on the terms you want the sides of the

vector diagram and its equivalent triangle to represent.

To refresh your memory, here are the three trig function formulas and the letter symbols

you have been using:

There are only four things to consider when using these formulas:

, side opposite,

side adjacent, and hypotenuse. If you aren't sure how to choose the correct function

formula, consider this:

First determine which side you are NOT interested in; namely, the side which is

not given and which you are not asked to find.

Now, reject the two formulas that contain this side. The remaining formula is the

one to use. Isolate the unknown and solve as before.

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