Determine whether each pair of expressions is equivalent.
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In triangle abc, the length of side ab is 12 cm, the length of side bc is 5 cm, and the length of side ca is 9 cm. find the measure of angle a using the law of cosines.

If sr is 4.5cm and tr is 3cm, what is the measure in degrees of angle s?

Joanie wrote a letter that was 1 1/4 pages long. katie wrote a letter that was 3/4 page shorter then joagies letter. how long was katies letter