- Home
- Standard 11
- Mathematics
9.Straight Line
normal
The co-ordinates of the orthocentre of the triangle bounded by the lines, $4x - 7y + 10 = 0; x + y=5$ and $7x + 4y = 15$ is :
A
$(2, 1)$
B
$(- 1, 2)$
C
$(1, 2)$
D
$(1, - 2)$
Solution
Given lines $4 x-7 y+10=0—-(1)$
$x+y-5=0—-(2)$
$7 x+4 y-15=0—-(3)$
On solving eq ( 1 ) and ( 3 ) $7 x+4\left(\frac{4 x+10}{7}\right)-15=0$
$49 x+16 x+40-105=0$
$65 x=65 \Rightarrow x=1$
From eq (1) $4-7 y=-10$
$-7 y=-14$
$y=2$
Point of intersection is (1,2) Here Equation (1) and (3) are perpendicular So the lines formed right angle triangle Hence the orthocentre of Right angle triangle is the point at which $90^{0}$ angle is formed Hence (1,2) is orthocentre
Standard 11
Mathematics