How many points with integer coordinates are in the triangle with vertices #(0, 0)#, #(0, 21)# and #(21, 0)#, including the points on its boundary?
1 Answer
Jan 6, 2018
Explanation:
The number of integral points on the diagonal line segment joining
So there are
So the total number of integral points in the triangle is:
#sum_(n=1)^22 n = 1/2 (color(blue)(22))(color(blue)(22)+1) = 253#