KVPY2020MathematicsProperties of Triangles
Let a = B C ,   b = C A ,   c = A B be the side lengths of a triangle A B C , and m be the length of the median through A . If a = 8 ,   b - c = 2 ,   m = 6 then the nearest integer to b is
Options
- A7
- B8
- C9
- D10
Correct answer
B. 8
Step-by-step solution
m 2 = 2   b 2 + 2 c 2 - a 2 4 ⇒ 144 + 64 = 2   b 2 + ( b - 2 ) 2 ⇒ 104 = 2 b 2 - 4 b + 4 ⇒ b 2 - 2 b - 50 = 0 ⇒ ( b - 1 ) 2 = 51 ⇒ b = 1 + 51 ∈ ( 8 , 9 )