Answer:
NO.
15, 35, 40 it will make an obtuse triangle.
Explanation:
If a ≤ b ≤ c are sides of a triangle, then a + b > c.
We have a = 15, b = 35, c = 40.
Check:
15 + 35 = 50 > 40 CORRECT
These sides can be the sides of a triangle.
If a ≤ b ≤ c are sides of a triangle, then
if a² + b² = c², then it's a right triangle
if a² + b² < c², then it's an obtuse triangle
if a² + b² > c², then it's an acute triangle
Check:
15² + 35² = 225 + 1225 = 1450
40² = 1600
1450 < 1600 ⇒ 15² + 35² < 40²
Therefore it's an obtuse triangle