In △ABC, the ratio of altitudes BE and CF is equal to one. What can be said about the nature of △ABC?
Isoceles
Given: BE = FC
In △ABE and △ACF,
∠A = ∠A (common angle)
∠AEB = ∠AFC = 90∘
BE = FC (given)
△ABE and △ACF are congruent by AAS property of congruence, because two angles and a side of one triangle are equal to corresponding two angles and a side of the other triangle.
Therefore, corresponding sides and angles will be equal.
So, AB = AC. Therefore, △ABC is an isoscles triangle.