How many triangles are there in the figure ?

11 12 13 14

13

Here When n is odd: No. of triangles = \(\frac{n\;(n\;+\;2)(2n\;+\;1)\;-\;1}{8}\)                        = \(\frac{3\;(3\;+\;2)(6\;+\;1)\;-\;1}{8}\)                        = \(\frac{105\;-\;1}{8}\) = 13