A line passes through A(3, 7), and B(-4, 9). Find the value of a if C(a, 1) is on the line.
slope is (9-7)/(-4-3)=-2/7. So y=-2/7x+b --> 7=-2/7*3+b --> b=55/7. So y=-2/7x+55/7 --> when y=1 --> 1=-2/7a+55/7 --> a=24
a = (7 - 1) / arctan(2 / 7) + 3 = 24
+605 
