If `m_1` and `m_2` are the roots of the equation `x^2-a x-a-1=0` , then the area of the triangle formed by the three straight lines `y=m_1x ,y=m_2x ,` and `y=a(a!=-1)` is
`1.` `(a^2(a+2))/(2(a+1))ifa > -1`
` 2.``(-a^2(a+2))/(2(a+1))ifa > -1`
` 3.``(-a^2(a+2))/(2(a+1))` if `-2 < a < -1`
`4.` `(a^2(a+2))=(2(a+1))` if `a < -2`