What mathematical technique did Galileo use to estimate the height of the lunar mountains?

Answer

Measuring the angles at which sunlight first struck their peaks as they emerged from shadow.

Galileo applied an early form of trigonometry by measuring the angles of illumination on the mountain peaks as they emerged from the shadow line to calculate their vertical height.

What mathematical technique did Galileo use to estimate the height of the lunar mountains?
HistoryGalileoastronomytelescopeMoonobservations