If tan A = a / b, a (is greater than sign) 0, b (is greater than sign) 0, and 0 is (less than sign) A (is less than sign) pi / 2, then what is cos A?

Question

a. a / b
B. b / a
C. a / radical(a^2 + b^2)
D. b / radical(a^2 + b^2)
E. radical(a^2 + b^2) / b

Answer 1

why all those words? Try using a little actual notation:

If tan A = a / b, a>0, b>0, and 0<A<pi/2, then what is cos A?

a. a / b
B. b / a
C. a / √(a^2 + b^2)
D. b / √(a^2 + b^2)
E. √(a^2 + b^2) / b

given tanA = a/b, you know that
opposite side is a
adjacent side is b
hypotenuse is √(a^2+b^2)

so, what is the definition of cosA?