Maths Help! Sprit of Math Catalan sequence question. Grade 9.?

The formula 180(n-2) gives the number of degrees in the angles of a convex polygon because n-2 triangles can be drawn (with no lines crossing) in a polygon with n sides, each triangle containing 180. In how many ways can a convex heptagon be divided into five triangles if each divided into five triangles if each... show more The formula 180(n-2) gives the number of degrees in the angles of a convex polygon because n-2 triangles can be drawn (with no lines crossing) in a polygon with n sides, each triangle containing 180. In how many ways can a convex heptagon be divided into five triangles if each divided into five triangles if each different orientation is counted separately? (Hint: look up the Catalan sequence)
(A) 6
(B) 36
(C) 42
(D) 48
(E) 52
2 answers 2