# math

posted by .

a diagonal of a polygon is a straight line joining any 2 non-adjacent corners.a decagon has 10 corners. .how many diagonals does it have ?

• math -

Joining any two points will produce a line
there are C(10,2) such lines or 45 of them
But, 10 of them will be the actual sides of the polygon, the others are diagonals

number of diagonals = 45-10 = 35

• math -

## Similar Questions

1. ### Physics

Two adjacent corners of a square have charges q1 = +1.5 x 10-9 C and q2 = +4.0 x 10-9 C. The length of a side of the square L = 0.25 m. Find the EPE of a charge q3= -6.0 x 10-9 C placed at the 2 remaining corners.
2. ### math

a square foot tile has a decorative line connected the diagonal corners. If the sides of the tile are 12 inches, what is the length of the diagonal to the nearest tenth?
3. ### geometry

If a polygon is a kite, which statement is not true?
4. ### physics

Identical +3.07 µC charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total electric potential at the remaining empty corner is 0 …
5. ### Math

we are working on a puzzle similar to a magic square. 9 boxes are arranged in an X with the center box being shared by both diagonals. the goal is to use each integer 1-9 one time so that each diagonal sums to 26 and the 4 corners …
6. ### geometry

A polygon has d diagonals. If the polygon had one more side, it would d + 10 diagonals. How many sides does the polygon have?
7. ### physics

Identical +1.39 µC charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total electric potential at the remaining empty corner is 0 …
8. ### Physics

Identical +6.15 µC charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total electric potential at the remaining empty corner is 0 …
9. ### Physics

Identical +3.92 ìC charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total potential at the remaining empty corner is 0 V?
10. ### physics

Each charge of 3 micro coulomb are placed at 3 corners of a square whose diagonal is 6cm long. Find the field intensity at the point of intersection of diagonals

More Similar Questions