$\text{Đáp án:}$
$A=\cot(89^o)×\cot(1^o)+\dfrac{3}{4}$
$=\cot(89^o)×\tan(90^o-1^o)+\dfrac{3}{4}$
$=\cot(89^o)×\tan(89^o)+\dfrac{3}{4}$
$=1+\dfrac{3}{4}$
$=\dfrac{7}{4}$
$B=\dfrac{\cos(55^o)}{\sin(45^o)}+1$
$=\dfrac{\cos(55^o)}{\cos(90^o-45^o)}+1$
$=\dfrac{\cos(55^o)}{\cos(55^o)}+1$
$=1+1$
$=2$