## Thomas' Calculus 13th Edition

a. $a/c$ b. $\sqrt {1-b^2/c^2}$
a. Express sin A in terms of a and c. $sin(A)=a/c$ b. Express sin A in terms of b and c. $sin(A)=a/c=\sqrt {c^2-b^2}/c=\sqrt {1-b^2/c^2}$