Oblicz wartość wyrażenia nie korzystając z tablic matemattycznych
a) sin^2 20 stopni + sin ^2 70 stopni
b)
a)b)
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a)
![sin^2 20^o + sin^2 70^o=sin^2 20^o + [sin(90^o-20^o)]^2=sin^2 20^o + cos^2(20^o)=1 sin^2 20^o + sin^2 70^o=sin^2 20^o + [sin(90^o-20^o)]^2=sin^2 20^o + cos^2(20^o)=1](https://tex.z-dn.net/?f=sin%5E2+20%5Eo+%2B+sin%5E2+70%5Eo%3Dsin%5E2+20%5Eo+%2B+%5Bsin%2890%5Eo-20%5Eo%29%5D%5E2%3Dsin%5E2+20%5Eo+%2B+cos%5E2%2820%5Eo%29%3D1)
![cos^2 15^o+ cos ^2 105^0=cos^2 15^o+ [cos(90^o+15^o)]^2=cos^2 15^o+ [-sin 15^o]^2=cos^2 15^o+ sin^2 15^o=1 cos^2 15^o+ cos ^2 105^0=cos^2 15^o+ [cos(90^o+15^o)]^2=cos^2 15^o+ [-sin 15^o]^2=cos^2 15^o+ sin^2 15^o=1](https://tex.z-dn.net/?f=cos%5E2+15%5Eo%2B+cos+%5E2+105%5E0%3Dcos%5E2+15%5Eo%2B+%5Bcos%2890%5Eo%2B15%5Eo%29%5D%5E2%3Dcos%5E2+15%5Eo%2B+%5B-sin+15%5Eo%5D%5E2%3Dcos%5E2+15%5Eo%2B+sin%5E2+15%5Eo%3D1)
b)