The exact value is <span>sin<span>(arccos<span>(<span>3/4</span>)</span>)</span></span>The equation for cosine is <span>cos<span>(A)</span>=<span>AdjacentHypotenuse</span></span>. The inside trig function is <span>arccos<span>(<span>3/4</span>)</span></span>, which means <span>cos<span>(A)</span>=<span>3/4</span></span>. Comparing <span>cos<span>(A)</span>=<span>AdjacentHypotenuse</span></span> with <span>cos<span>(A)</span>=<span>3/4</span></span>, find <span>Adjacent=3</span> and <span>Hypotenuse=4</span>. Then, using the pythagorean theorem, find <span>Opposite=<span>√7</span></span>.<span>Adjacent=3</span><span>Opposite=<span>√7</span></span><span>Hypotenuse=4</span>Substitute in the known variables for the equation <span>sin<span>(A)</span>=<span>OppositeHypotenuse</span></span>.<span>sin<span>(A)</span>=<span><span>√7</span> over 4</span></span>Simplify.<span><span>√7</span><span> over 4</span></span>
One of the answers is equilateral because all of the sides are of equal length. The other answer is acute because all of the angles are under 90º since they are all 60º. Hope this helps!
