A) Right angled
B) Equilateral
C) Obtuse angled
D) None of these
Correct Answer: C
Solution :
Let \[a=3x+4y,\,b=4x+3y\] and \[c=5x+5y\]. Clearly, c is the largest side and thus the largest angle C is given by \[\cos C=\frac{{{a}^{2}}+{{b}^{2}}-{{c}^{2}}}{2ab}=\frac{-2xy}{2\,(12{{x}^{2}}+25xy+12{{y}^{2}})}<0\] \[\Rightarrow \] \[C\] is an obtuse angle. Trick: Check by putting\[x=1,\] \[y=1\].
You need to login to perform this action.
You will be redirected in
3 sec
