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ICSE Class X Math 2013 Paper

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Question : 44 of 46
Marks: +1, -0
In the figure given below, the line segment ABA B meets XX -axis at AA and YY -axis at BB . The point P(−3,4)P(-3,4) on ABA B divides it in the ratio 2 : 3. Find the coordinates of AA and BB.
Solution:  
Let the co-ordinates of AA and BB be (x,0)(x, 0) and (0,y)(0, y)
∵\because The co-ordinates of a point P(−3,4)P(-3,4) on {AB}\{AB\} divides it in the ratio 2:32: 3 .
i.e., {AP}:{PB}=2:3\{AP\}:\{PB\}=2: 3
By using section formula,
x  =  m1x2+m2x1m1+m2x\;=\;\frac{m_1 x_2+m_2 x_1}{m_1+m_2}
−3  =  2×0+3×x2+3-3\;=\;\frac{2 \times 0+3 \times x}{2+3}
⇒    −3  =  3x5⇒3x=−15\Rightarrow \;\; -3\;=\;\frac{3 x}{5} \Rightarrow 3 x=-15
x  =−5x\;=-5
and y  =  m1y2+m2y1m1+m2y\;=\;\frac{m_1 y_2+m_2 y_1}{m_1+m_2}
4  =  2×y+3×02+34\;=\;\frac{2 \times y+3 \times 0}{2+3}
⇒  4  =  2y5\Rightarrow\;4\;=\;\frac{2 y}{5}
⇒2y  =20\Rightarrow 2 y\;=20
⇒y  =10\Rightarrow y\;=10
Hence, the co-ordinates of AA and BB are ( -5 , 0)0) and (0,10)(0,10). .
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