Hãy tính
a) 2sin300 - 2cos600 + tg450;
b) sin450 + cotg600.cos300;
c) cotg440.cotg450.cotg460.
a) 2sin30o - 2cos60o + tg45o = tg45o = 1 (do sin30o = cos60o).
b) sin45o + cotg60o.cos30o = (1+ √2)/2.
c) cotg44o.cotg45o.cotg46o = cotg45o = 1
(vì cotg44o = tg46o do 44o + 46o = 90o mà tg46o.cotg46o = 1)
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