INVERSE TRIG FUNCTIONS Expressions (Page 5 of 8)

When solving problems that involve the Law of Cosines, it may be necessary to evaluate an expression such as arccos((10^2+12^2-15^2)/(2(10)(12))).

 CLEAR key.

 2nd inverse cosine key. Left parenthesis key. 10 x-squared key. Plus key. 12 x-squared key. Minus key. 15 x-squared key. Right parenthesis key.
 Divide key. Left parenthesis key. 2 Multiply key. 10 Multiply key. 12 Right parenthesis key. Right parenthesis key. ENTER key.

 Calculator screen image.

Notice the need for additional parentheses around the numerator and around the denominator. To the nearest tenth degree, the angle would have measure of approximately 85.5°.
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