wartość wyrażenia
: 28 sty 2014, o 20:54
Proszę o sprawdzenie (ew. wytłumaczenie jak coś źle robię):
1) \(\displaystyle{ \sin \left( 2\arccos \frac{1}{5}\right)}\)
\(\displaystyle{ \sin^2 \left( 2\arccos \frac{1}{5} \right) =1-2\cos ^2 \left( \arccos \frac{1}{5} \right) =1-2 \cdot \left( \frac{1}{5} \right) ^2= \frac{24}{25}}\)
\(\displaystyle{ \sin \left( 2\arccos \frac{1}{5} \right) = \sqrt{ \frac{24}{25} } = \frac{ \sqrt{24} }{5}}\)
2) \(\displaystyle{ \cos \left( 2\arcsin \frac{1}{7} \right)}\)
\(\displaystyle{ \cos^2 \left( 2\arcsin \frac{1}{7} \right) =1-2\sin ^2 \left( \arcsin \frac{1}{7} \right) =1-2 \cdot \left( \frac{1}{7} \right) ^2= \frac{6}{7}}\)
\(\displaystyle{ \cos \left( 2\arcsin \frac{1}{7} \right) = \sqrt{ \frac{6}{7} }}\)
1) \(\displaystyle{ \sin \left( 2\arccos \frac{1}{5}\right)}\)
\(\displaystyle{ \sin^2 \left( 2\arccos \frac{1}{5} \right) =1-2\cos ^2 \left( \arccos \frac{1}{5} \right) =1-2 \cdot \left( \frac{1}{5} \right) ^2= \frac{24}{25}}\)
\(\displaystyle{ \sin \left( 2\arccos \frac{1}{5} \right) = \sqrt{ \frac{24}{25} } = \frac{ \sqrt{24} }{5}}\)
2) \(\displaystyle{ \cos \left( 2\arcsin \frac{1}{7} \right)}\)
\(\displaystyle{ \cos^2 \left( 2\arcsin \frac{1}{7} \right) =1-2\sin ^2 \left( \arcsin \frac{1}{7} \right) =1-2 \cdot \left( \frac{1}{7} \right) ^2= \frac{6}{7}}\)
\(\displaystyle{ \cos \left( 2\arcsin \frac{1}{7} \right) = \sqrt{ \frac{6}{7} }}\)