The points A(0, 0), B(0, 4a - 2) and C(2a + 1, 2a + 6) form a triangle. If angle ABC = 90, what is the area of triangle ABC?	Select.
A) 58  B) 70  C) 63  D) 65  E) 72
1/2bh=1/2(2a+1)(2a+6)   Now 4a-2=2a+6   2a 4 -2= 
<gadget id="calculator"> 4 -2</gadget>
<output>2</output>
2a+6   2a=8 . a=4   Therefore,   A(0,0); B(0,14); 63(9,14)   1/2*9*14= 
<gadget id="calculator">1/2*9*14</gadget>
<output>63</output>
63   Answer: 63
<result>C</result>
The points A(0, 0), B(0, 4a - 2) and C(2a + 1, 2a + 6) form a triangle. If angle ABC = 90, what is the area of triangle ABC?