Two sides of an isosceles triangle are 4 cm and 10 cm
In an isosceles triangle two sides are equal.
Case 1:
Let the third side be 4 cm.
For any triangle with sides let say a,b,c, then
a+b>c and
c+b>a and
c+a>b
In this case 4+4=8<10
So, the third side of 4 cm will not possible.
Case 2:
Let third side be 10 cm
10+4=14>10 and
10+10=20>10
Therefore, 10 cm is the third side.
Hence, the length of the third side is 10 cm.