Q.
The joint equation of two altitudes of an equilateral triangle is
(3​x−y+8−43​)(−3​x−y+12+43​)=0
The third altitude has the equation
Clearly, the third altitude will be the bisector of obtuse angle between the given altitudes.
Now given two altitudes are 3​x−y+8−43​=0 .... (i)
and −3​x−y+12+43​=0 .....(ii) a1​a2​+b1​b2​=−3​3​+(−1)(−1)=−2<0 ∴ Obtuse angle bisector is: 3+13​x−y+8−43​​=−3+1−3​x−y+12+43​​
or y=10