Bonjour,
[tex]A= cos \frac{ \pi }{4}+cos \frac{ \pi }{3} +cos \frac{ \pi }{2} \\
= \dfrac{ \sqrt{2} }{2} + \dfrac{1}{2} +0\\
= \dfrac{1+ \sqrt{2} }{2} \\\\\\
B= \dfrac{sin \dfrac{ 3\pi}{4} *cos \dfrac{ 2\pi }{3}}{sin \dfrac{ -\pi}{3} *cos \dfrac{ \pi }{4}} \\\\
=\dfrac{\dfrac{ \sqrt{2} }{2} * \dfrac{ -1 }{2}}{\dfrac{- \sqrt{3} }{2}*\dfrac{ \sqrt{2} }{2} }\\\\
=\dfrac{1}{ \sqrt{3} }\\\\
=\dfrac{ \sqrt{3} }{3}\\\\
[/tex]
