Vikas TU
Last Activity: 7 Years ago
This is a privilege calculated triangle with right point at source
presently consider (0,0) ,(0,1),(0,2) ...(0,41) we have 41 focuses
next consider(1,0),(1,1),(1,2) ...(1,40) we have 40 focuses
so no of focuses inside the triangle and on limit together are
41+40+39+38+......1
so add up to no of focuses =(41)(42)/2 = 861
presently we have 81 focuses on limit
therfore reqd no of focuses = 861-80= 780
