Is in the sin theta = a^2 - b^2 / a^2 + b^2 then find the value of cos theta

Since sin theta= perpendicular/hypotenuse=> perpendicular=(a^2-b^2) and hypotenuse=(a^2+b^2). As we know that in a right angle triangle, hypotenuse^2=base^2+ perpendicular^2. When we will put the values of perpendicular and hypotenuse, we`ll get base =2ab.Since cos theta= base/hypotenuse=>cos theta= 2ab/(a^2+b^2).HOPE IT HELPED. BEST OF LUCK:)