Question

find the value of cos^2 20°+cos ^2 70°/sin^2 59°+son^2 31°

Answer 1

$= \frac{cos^{2} 20 + cos^{2} 70}{sin^{2} 59+ sin^{2}31} \\ \\ = \frac{cos^{2}20+cos^{2} (90-20)}{sin^{2}59+sin^{2}(90-59)} \\ \\ = \frac{cos^{2}20+sin^{2}20}{sin^{2}59+cos^{2}59} \\ \\ = \frac{1}{1} \\ \\ = 1 \\ \\ identity - used : sin^{2}A + cos^{2}A = 1$