J & K CET Engineering J and K - CET Engineering Solved Paper-2003

  • question_answer
    In a triangle ABC, \[C={{90}^{o}}\]. If r is the in radius and R is the circum radius of the triangle, then \[2\,(r+R)\]is equal to

    A)  \[a+c\]        

    B)  \[a+b+c\]

    C)  \[b+c\]        

    D)  \[a+b\]

    Correct Answer: D

    Solution :

    We know that \[\frac{c}{\sin \,C}=2R\] \[(\because \,\,\angle C={{90}^{o}})\] \[\Rightarrow \] \[c=\,2R\] ?..(i) and \[\tan \frac{C}{2}=\frac{r}{s-c}\] \[\Rightarrow \] \[\tan \,\,{{45}^{o}}=\frac{r}{s-c}\] \[\Rightarrow \] \[r=s-c\] \[\Rightarrow \] \[r=\frac{a+b+c}{2}-c\] \[\Rightarrow \] \[2r=a+b-c\] On adding Eqs. (i) and (ii), we get       \[2(r+R)=a+b\]


You need to login to perform this action.
You will be redirected in 3 sec spinner