To find the cost of a frame of a picture, we need to find the perimeter of the picture.
Why perimeter?
• A frame goes all around the edge of the picture.
• The total length around the edge is called the perimeter.
So, to find the cost:
1) First find how much frame material is needed. That is the perimeter.
2) Then multiply this length by the cost per unit length (like per cm or per m).
Perimeter of a rectangle (most pictures are rectangular):
Let the picture have length ( ell ) and breadth ( b ).
The perimeter is:
\[ P = 2(ell + b) \]
Example idea:
If ( ell = 20 ext{ cm} ) and ( b = 15 ext{ cm} ), then
\[ P = 2(20 + 15) = 2 imes 35 = 70 ext{ cm}. \]
If the frame costs ₹( 5 ) per cm, total cost = ( 70 imes 5 = ₹350 ).
Conclusion: Because the frame covers only the boundary, we must find the perimeter to get its cost. Hence, the statement is true.