sin²a+cos²=1
sin²=1-cos²
sin²= 1-(-0,6)²=1-0,36=0,64
sin=√0,64=0,8
tga=sina/cosa
tga=8/10÷6/10=8/10×10/6=4/3
sin²a+cos²=1
sin²=1-cos²
sin²= 1-(-0,6)²=1-0,36=0,64
sin=√0,64=0,8
tga=sina/cosa
tga=8/10÷6/10=8/10×10/6=4/3