1.若α、β、γ都是銳角，且tanα=1/2、tanβ=1/5、tanγ=1/8，則α+β+γ=？

答案：登入後查看
統計： A(23), B(26), C(37), D(33), E(0) #1310905

詳解 (共 2 筆)

#1451000
tan(β+γ)=(tanβ+tanγ)/(1-tanβ x tanγ)=(1/5+1/8)/(1-1/5x1/8)=(13/40)/(39/40)=1/3
tan(α+β+γ)=(tanα+tan(β+γ))/(1-tanα x tan(β+γ))=(1/2+1/3)/(1-1/2 x 1/3)=(5/6)/(5/6)=1
α+β+γ=45°
2
0
#1414367
D
0
1