tgα= sinα/cosα, sin^2 α + cos^2 α = 1, sinα = √ (1 – cos^2 α), sinα = √ (1 – 144/169) = √ 25/169 = 5/13, tgα = 5/13|12/13 = 5/12.
Відповідь: tgα = 5/12
