In the verge of coronavirus pandemic, we are providing FREE access to our entire Online Curriculum to ensure Learning Doesn't STOP!

Ex.6.5 Q5 Triangles Solution - NCERT Maths Class 10

Go back to  'Ex.6.5'


\(ABC\) is an isosceles triangle with \({AC = BC}\). If \(A B^{2}=2 A C^{2}\) prove that \(ABC\) is a right triangle.


 Video Solution
Ex 6.5 | Question 5

Text Solution


As we know ,In a triangle, if square of one side is equal to the sum of the squares of the other two sides, then the angle opposite the first side is a right angle.


In \(\Delta A B C\)

\[AC = BC\]


\[\begin{align}A B^{2} &=2 A C^{2} \\ &=A C^{2}+A C^{2} \\ A B^{2} &=A C^{2}+B C^{2}  \quad[\because A C=B C] \end{align}\]

\(\Rightarrow \angle A C B=90^\circ\)

\(\begin{align}\Rightarrow \Delta A B C \end{align}\) is a right triangle