Then somehow it says therefore tan^2-1 = sec^2 so it replaces the entire first argument with sec^2, completely ignoring that 1 we were supposed to deduct from tan. So sin^2/cos^2 + cos^2/cos^2 = 1/cos^2 and 1/cos^2 is sec^2 << still following The solutions tell us to divide both sides by cos^2. Tan^2 = sin^2+cos^2 = 1 << this we can agree on Start by simplifying the tan^2 theta angle We must simplify (tan^2 theta - 1) <<<< note the 1 within this argument, we're taking an angle, and deducting 1 How is tan squared less 1 = secant? Each question for this section uses this central calculation to simplify the calculations, but it makes no logical sense