Evaluate <span><span>cos<span>(10)</span></span><span>cos10</span></span> to get <span>0.984807750.98480775</span>.<span><span><span>0.98480775<span>cos<span>(80)</span></span></span><span><span>−<span>sin<span>(10)</span></span></span><span>sin<span>(80)</span></span></span></span><span><span>0.98480775<span>cos80</span></span><span><span>-<span>sin10</span></span><span>sin80</span></span></span></span>Evaluate <span><span>cos<span>(80)</span></span><span>cos80</span></span> to get <span>0.173648170.17364817</span>.<span><span><span>0.98480775⋅0.17364817</span><span><span>−<span>sin<span>(10)</span></span></span><span>sin<span>(80)</span></span></span></span><span><span>0.98480775⋅0.17364817</span><span><span>-<span>sin10</span></span><span>sin80</span></span></span></span>Multiply <span>0.984807750.98480775</span> by <span>0.173648170.17364817</span> to get <span>0.171010070.17101007</span>.<span><span>0.17101007<span><span>−<span>sin<span>(10)</span></span></span><span>sin<span>(80)</span></span></span></span><span>0.17101007<span><span>-<span>sin10</span></span><span>sin80</span></span></span></span>Evaluate <span><span>sin<span>(10)</span></span><span>sin10</span></span> to get <span>0.173648170.17364817</span>.<span><span>0.17101007<span><span><span>−1</span>⋅0.17364817</span><span>sin<span>(80)</span></span></span></span><span>0.17101007<span><span><span>-1</span>⋅0.17364817</span><span>sin80</span></span></span></span>Multiply <span><span>−1</span><span>-1</span></span> by <span>0.173648170.17364817</span> to get <span><span>−0.17364817</span><span>-0.17364817</span></span>.<span><span>0.17101007<span><span>−0.17364817</span><span>sin<span>(80)</span></span></span></span><span>0.17101007<span><span>-0.17364817</span><span>sin80</span></span></span></span>Evaluate <span><span>sin<span>(80)</span></span><span>sin80</span></span> to get <span>0.984807750.98480775</span>.<span><span>0.17101007<span><span>−0.17364817</span>⋅0.98480775</span></span><span>0.17101007<span><span>-0.17364817</span>⋅0.98480775</span></span></span>Multiply <span><span>−0.17364817</span><span>-0.17364817</span></span> by <span>0.984807750.98480775</span> to get <span><span>−0.17101007</span><span>-0.17101007</span></span>.<span><span>0.17101007<span>−0.17101007</span></span><span>0.17101007<span>-0.17101007</span></span></span>Subtract <span>0.171010070.17101007</span> from <span>0.171010070.17101007</span> to get <span>0</span>.0
