The midpoint k connects MK and lk.

Then there is MK∨AH∨OL,

LK∨BH∨OM。

∴ Quadrilateral OLKM is a parallelogram.

∴MK=OL.

∴AH=2OL.

Method (2):

Extend BO to d, and connect CD and AD.

Then CD = 2OL. ..

And ∵CD⊥BC, AH⊥BC,

∴CD∥AH.

Similarly, ad∨ch.

∴ Quadrilateral AHCD is a parallelogram.

∴AH=CD.

∴AH=2OL.