Figs. Below gives a matchstick pattern of triangles. As in Exercise 11 (a) above find the general rule that gives the number of matchsticks in terms of the number of triangles.
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Look at the following matchstick pattern of squares. The squares are not separate. Two neighboring squares have a common matchstick. Observe the patterns and find the rule that gives the number of matchsticks in terms of the number of squares. (Hint: If you remove the vertical stick at the end, you will get a pattern of Cs.) .

Look at the match sticks patterns of squares. The squares are not separate. Two neighbouring square have a common match stick. Observe the patterns and find the rule take gives the number of match sticks in term of numbr of squares.

Give the term for the number of organismsper unit area.

Can you write the rule for making pattern for F? Table given below gives the number of match sticks required to make a pattern of Fs.