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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 9: Tính A=cot89°×cot1°÷3phaanf4 B=cos55°trên sin45°+1 (Giúp e với ạ)

Toán Lớp 9: Tính
A=cot89°×cot1°÷3phaanf4
B=cos55°trên sin45°+1
(Giúp e với ạ)

Comments ( 1 )

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

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222-9+11+12:2*14+14 = ? ( )