Question

(1-sin^2(270°+a))/(1-sin^2(180°+a))=

Answer 1

$frac{1-sin^2(270^circ +a)}{1-sin^2(180^circ +a)} = frac{1-cos^2a}{1-sin^2a} = frac{sin^2a}{cos^2a} =tg^2a$