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Please solve RD Sharma class 12 chapter Determinants exercise 5.3 question 13 subquestion (i) maths textbook solution

Answers (1)

Answer: k=0

Hints: Putting the values of vertices, in the formula of area of triangle.

Given: (k,0), (4,0) and (0,2)
              area of triangle= 4 sq. units

Explanation: Vertices are (k,0), (4,0) and (0,2)

\text { Area of triangle is }=\Delta=\frac{1}{2}\left|\begin{array}{lll} X_{1} & Y_{1} & 1 \\ X_{2} & Y_{2} & 1 \\ X_{3} & Y_{3} & 1 \end{array}\right|=4

\Rightarrow \Delta=\frac{1}{2}\left|\begin{array}{lll} k & 0 & 1 \\ 4 & 0 & 1 \\ 0 & 2 & 1 \end{array}\right|=4

\Delta=\frac{1}{2}\left(k\left|\begin{array}{cc} 0 & 1 \\ 2 & 1 \end{array}\right|-0\left|\begin{array}{cc} 4 & 1 \\ 0 & 1 \end{array}\right|+1\left|\begin{array}{cc} 4 & 0 \\ 0 & 2 \end{array}\right|\right)=4

     = \frac{1}{2}[k(0-2)-0+1(8-0)]=4

     \Rightarrow -2k+8=8

     \Rightarrow -2k=0

     \Rightarrow k=0

Posted by

Gurleen Kaur

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