Question

(sin2a-cos2a) / (sin2a+cos2a)
 Если tga = 0,5

Answer 1

$\frac{sin2a-cos2a}{sin2a+cos2a}=\frac{tg2a-1}{tg2a+1}=\frac{\frac{2tga}{1-tg^{2}a}-1}{\frac{2tga}{1-tg^{2}a}+1}=\frac{2tga-1+tg^{2}a}{2tga+1-tg^{2}a}=\frac{2*0.5-1+0.5^{2}}{2*0.5+1-0.5^{2}}=\frac{0.25}{2-0.25}=\frac{0.25}{1.75}=\frac{25}{175}=\frac{1}{7}$