Oblicz bez uzycia tablicy

[alaz6]

a)\(\displaystyle{ (\sin 25^\circ+\cos 25^\circ)(\sin 25^\circ- \cos 25^\circ) + 2 \sin^2}\)
b)\(\displaystyle{ \cos^2 80^\circ+ \cos^2 80^\circ}\)
c)\(\displaystyle{ (\cos 17^\circ + \cos 73^\circ)^2+(\sin 17^\circ-\sin 73^\circ)^2}\)
d)\(\displaystyle{ \ctg 10^\circ\cdot \ctg 20^\circ\cdot\ctg 30^\circ\cdot\ctg 40^\circ\cdot\ctg50^\circ\cdot\ctg60^\circ\cdot\ctg70^\circ\cdot\ctg80^\circ}\)


"Urzycia" ta? Lorek