Brother Chao teaches mathematics.

Because tanA= 0.25.tanB=0.6.

So tan (a+b) = (tana+tanb)/(1-tana * tanb) = (0.25+0.6)/(1-0.25 * 0.6) = 0.85/(1-0).

Because it is in a triangle, A+B=45 degrees.

So C= 180 degrees -(A+B)= 135 degrees.

tanA=0.25= 1/4=sinA/cosA

So Sina = 1/ root number 17.

So according to the sine theorem,

a/sinA=c/sinC

That's BC/sinA=AB/sinC.

That is BC=AB*sinA/sinC= number of radicals 17*( 1/ number of radicals 17)/sin 135 degrees =1(number of radicals 2 /2)= number of radicals 2.