# the ortho center of the triangle formed by the lines x+y+1=0,x-y-1=0,3x+4y+5=0 is ?

The lines x+y+1 =0 and x-y-1 = 0 are perpendicular

as product of slopes = -1

So the triangle is right angled.

The two line intersect at (0,-1)

Orthocenter is the point of intersection of the altitudes. Each leg in a right triangle forms an altitude. So, in a right-angled triangle, the orthocenter lies at the vertex containing the right angle.

So orthocenter is (0,-1)

Regards

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