Question

how many diagonals in a triangles and quadrilateral have ?​

Answer 1

Answer:

two diagonals

So a triangle, the simplest polygon, has no diagonals. You cannot draw a line from one interior angle to any other interior angle that is not also a side of the triangle. A quadrilateral, the next-simplest, has two diagonals. A pentagon, whether regular or irregular, has five diagonals.

Answer 2

Answer:

In a triangle there is no diagonals and in quadrilateral if it is convex then it has two diagonals and if it is concave than it has no diagonals.