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Calculează:
a) (sin 30° + cos 45º) x (sin 30° - cos 45º);
b) cos 45º x sin 45° + cos 60°;
c) (tg 45° + ctg 45°): cos 60°;
d) sin 60° x tg 30° - sin 30°.​

Răspuns :

a)(1/2+ rad din 2/2)×(1/2-rad din 2/2)= formula a patrat -b patrat=(1-2)/4=-1/4

b)rad 2/2×rad 2/2+1/2=2/4+1/2=1/2+1/2=2/2=1

c) (1+1)÷1/2=2÷1/2=2/1÷2/2=2/1×1=2

d)rad 3/2×rad 3/3-1/2=3/6-1/2=1/2-1/2=0

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