=( 1/4+3/5)/( 1- 1/4×3/5)

= 17/ 17

= 1

Because A+B+C=π

tanC = tan(π-A-B)=-tan(A+B)=- 1

So c = 135 (or 3/4π)

(2) According to the sine theorem in the triangle, we know that the side length corresponding to a large angle is the longest, and the side length corresponding to a small angle is the shortest.

0 & lttanA & lt A: A.

Sina = tanA/√ 1+ tan? A

=√ 17/ 17

sinC=√2/2

Sine theorem: a/c = Sina/sinc = √ 34/ 17.

a=√34/ 17c=√2

So the length of the smallest side is √2.