a-maths~~~~

在∆ABC,A:B:C=1:2:3,求a:b:c。
∵A:B:C = 1:2:3
Let A = x, B = 2x and C = 3x.
x + 2x + 3x = 180° (三角形的內角和)
x = 30°
∴A = 30°, B = 60°, C = 90°
根據正弦定律(sine formula)，
a/sin 30° = b/sin 60° = c/sin 90°
a/(1/2) = b/[√(3)/2] = c/1
a/1 = b/√3 = c/2
∴a:b:c = 1 : √3 : 2