cos²a+sin²a=1
cos²a=1-sin²a=1-144/169=25/169 cosa=-√25/169=-2/13
tga=sina/cosa=(12/13)/(-13/12)=-144/169
ctga=-169/144
cos²a+sin²a=1
cos²a=1-sin²a=1-144/169=25/169 cosa=-√25/169=-2/13
tga=sina/cosa=(12/13)/(-13/12)=-144/169
ctga=-169/144