Question

The co-ordinates of the points P and Q are (1,-2) and (4,10) respectively. A point T divides the line PQ in the ratio 2:1. Determine the co-ordinates of T

Answer 1

`\textit{internal division of a line segment using ratios} \\\\\\ P(1,-2)\qquad Q(4,10)\qquad \qquad \stackrel{\textit{ratio from P to Q}}{2:1} \\\\\\ \cfrac{P\underline{T}}{\underline{T} Q} = \cfrac{2}{1}\implies \cfrac{P}{Q} = \cfrac{2}{1}\implies 1P=2Q\implies 1(1,-2)=2(4,10)`

`(\stackrel{x}{1}~~,~~ \stackrel{y}{-2})=(\stackrel{x}{8}~~,~~ \stackrel{y}{20}) \implies T=\underset{\textit{sum of the ratios}}{\left( \cfrac{\stackrel{\textit{sum of x's}}{1 +8}}{2+1}~~,~~\cfrac{\stackrel{\textit{sum of y's}}{-2 +20}}{2+1} \right)} \\\\\\ T=\left( \cfrac{ 9 }{ 3 }~~,~~\cfrac{ 18}{ 3 } \right)\implies T=(3~~,~~6)`