Question 562537
Let x=AC and z=BA.  The third angle is 180-(20+90)=70 degrees.  To find x, we realize that the triangle is a right triangle with legs AC and CB and hypotenuse BA.  Therefore, 
{{{sin(70)=x/20}}}
so
{{{x=20sin(70)}}}
Further, we know that
{{{x^2+20^2=z^2}}}
So,
{{{z=sqrt(x^2+400)}}}