In the attached Quant Mountain entry, I can understand where two is coming at the base of the trapezoid, however, I am not able to understand where 2.5 is coming from.
Are we assuming here that the two triangles formed by dropping the perpendiculars are congruent?
Nothing has been mentioned about the magnitude of the angle to the left.
You’re right, they should’ve mentioned it was an isosceles trapezoid or something equivalent.
Which entry is this exactly?
Geometry 6 - Area of Trapezoid.
It’s actually “A Seemingly Impossible Problem III” - but fixed.