如题所述
根据余弦定理,有:
AB² = AC² + BC² - 2AC * BC * cos∠C
= 3 + 12 - 2×√3×2√3×cos120°
= 15 - 12×(-1/2)
= 21
那么,AB = √21
根据面积性质,有:
S△ABC = 1/2×AC×BC×sin∠C = 1/2×AB×h
所以:
h = AC×BC×sin120°/AB
= √3×2√3×(√3/2) /√21
= 3/√7
= 3√7 /7
第二小问能用初中的知识解答下么