Series Content LESSON 1 正弦定理 | Law of Sines LESSON 2 餘弦定理 | Law of Cosines LESSON 3 利用正弦計算三角形面積 | Finding Area of a Triangle by Sine Ratio LESSON 4 希羅公式 | Heron’s Formula LESSON 5 三角學的平面應用 | Application of Trigonometry in 2-D Problems