Given cot A= 8/15 and that angle A is in Quadrant I, find the exact value of cos A in simplest radical form using a rational denominator.

Answer 1

cotA = 8/15 = opposite side/adjacent side= o/a

hypotenuse squared = 8 squared + 15 squared

h^2 = 64 + 225 = 289 = 17^2

h=17

cosA = a/h = 15/17

No need for radicals

the triangle involved is a right triangle 8-15-17, with integer sides, making radicals unnecessary