The t = tan θ/2 substitution

In the right-angled triangle shown in Fig. 20.1, let angle B be equal https://www.w3.org/1998/Math/MathML"> θ 2 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315843629/20901bc5-1466-42ee-a7e4-0cc2fff34b68/content/inline-math_1881_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> to with side AB = 1, and side AC = t Figure 20.1 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315843629/20901bc5-1466-42ee-a7e4-0cc2fff34b68/content/fig20_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>