已知△ABC,∠A、∠B、∠C对应的边分别为a、b、c,A=30°,(1+√3)c=2b,求∠C
来源:百度知道 编辑:UC知道 时间:2024/07/03 16:00:41
b/c=(1+√3)/2
cosa=b^2+c^2-a^2/2bc
√3/2=(4+√3)/2*c^2-a^2/(1+√3)c^2
√3/2(1+√3)c^2=(4+√3/2)c^2-a^2
a^2=(4+√3/2-√3/2-3/2)c^2
a^2=5/2c^2
cosc=a^2+b^2-c^2/2ab
cosc=5/2c^2+(2+√3)/2c^2-c^2/2*√10/2c*(1+√3)/2c
cosc=[(5+√3)c^2/2]/(√10(1+√3)c^2/2)
cosc=(5+√3)/√10(1+√3)
cosc=(5+b/c=(1+√3)/2
cosa=b^2+c^2-a^2/2bc
√3/2=(4+√3)/2*c^2-a^2/(1+√3)c^2
√3/2(1+√3)c^2=(4+√3/2)c^2-a^2
a^2=(4+√3/2-√3/2-3/2)c^2
a^2=5/2c^2
cosc=a^2+b^2-c^2/2ab
cosc=5/2c^2+(2+√3)/2c^2-c^2/2*√10/2c*(1+√3)/2c
cosc=[(5+√3)c^2/2]/(√10(1+√3)c^2/2)
cosc=(5+√3)/√10(1+√3)
cosc=(5+b/c=(1+√3)/2
cosa=b^2+c^2-a^2/2bc
√3/2=(4+√3)/2*c^2-a^2/(1+√3)c^2
√3/2(1+√3)c^2=(4+√3/2)c^2-a^2
a^2=(4+√3/2-√3/2-3/2)c^2
a^2=5/2c^2
cosc=a^2+b^2-c^2/2ab
cosc=5/2c^2+(2+√3)/2c^2-c^2/2*√10/2c*(1+√3)/2c
cosc=[(5+√3)c^2/2]/(√10(1+√3)