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Exercises Trigonometry

Example 4 from Algebra and Trigonometry, 7.2 Right Triangle Trigonometry

Using Cofunction Identities

If $\sin t = \frac{5}{12},$ find $\cos (\frac{π}{2} - t) .$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
According to the cofunction identities for sine and cosine, we have the following.

$\sin t = \cos (\frac{π}{2} - t)$
So

$\cos (\frac{π}{2} - t) = \frac{5}{12}$

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

If $\csc (\frac{π}{6}) = 2,$ find $sec (\frac{π}{3}) .$

How did it go?

PreviousEvaluating Trigonometric Functions of Special Angles Using Side Lengths Next Finding Missing Side Lengths Using Trigonometric Ratios

From Algebra and Trigonometry (1st edition) by OpenStax (Rice University), section 7.2, licensed under CC BY 4.0. Original at openstax.org. We split the solution into steps; the words, numbers and figures are the book's. OpenStax doesn't endorse this site.