Q.

Orthocentre of triangle with vertices (0, 0), (3, 4) and (4, 0) is                       [2003]

1 (3,54)  
2 (3, 12)  
3 (3,34)  
4 (3, 9)  

Ans.

(3)

We know that point of intersection of altitudes of a triangle is the orthocentre of the triangle.

Equation of altitude AD i.e., line parallel to y-axis through (3,4) is

x=3                       (i)

Now, equation of OEAB is

y=-3-44-0x  y=x4                   (ii)

Solving (i) and (ii), we get orthocentre as (3,34)