I need help with trigonometry

One card is dealt from a 52 card deck. find the probability that the dealt card is a 4 or a black 7

Use the formulas a = x 2 – y 2, b = 2xy, c = x 2 + y 2 to answer this question. one leg of a right triangle has length 11 and all sides are whole numbers. find the lengths of the other two sides. the other leg = a0 and the hypotenuse = a1

Bring the fraction a/a-4 to a denominator of 16-a^2