text: Go back to your trig function definitions.  Suppose you have a right triangle with sides of length a and b, and hypotenuse of length c.  Let x be the angle between side b and hypotenuse c.  Then, using the symbol ^ to denote an exponent,\n\nsin (x) = a/c\ncos (x) = b/c\nsec (x) = 1/cos (x) = c/b\n\nThe squares are:\n\nsin^2 (x) = a^2 / c^2\ncos^2 (x) = b^2 / c^2\nsec^2 (x)  =  c^2 / b^2\n\nPlugging these definitions into your problem,\n\n(a^2 / c^2)  /  (b^2 / c^2)  =  (c^2 / b^2) - 1\n\nSimplifying,\n\na^2 / b^2  =  c^2 / b^2  -  1\n\nMultiplying by b^2,\n\na^2  =  c^2  -  b^2\n\nRearranging terms,\n\na^2  +  b^2  =  c^2\n\nwhich may be recognized as the Pythagorean Theorem.