When you see the word "perimeter", think of it as "peRIMeter". It has the word "RIM" inside. So "peRIMeter" just means to add around the RIM. So we add around the rim of the L: The line at the bottom is 3cm long The extreme right edge is 1cm long The horizontal upper part of the right side is 2cm long The vertical upper part is 3cm long The very top edge is 1cm long The extreme left side is 4cm long. Add them all up: 3cm + 1cm + 2cm + 3cm + 1cm + 4cm = 14cm That's the perimeter. Edwin