Altitudes AD and BE of triangle ABC intersect at H . If angle BAC = 54 degrees and angle ABC = 52 degrees, then what is angle AHB?
Since angle(BAC) = 54o and angle(ABC) = 52o, angle(BCA) = 180o - 54o - 52o = 74o.
Look at quadrilateral(DCEH):
-- since AD is an altitude, angle(CDA) = 90o
-- since BE is an altitude, angle(CEB) = 90o
-- since there are 360o in a quadrilateral: angle(CDA) + angle(CEB) + angle(BCA) + angle(DHE) = 360o
-- substituting, we get angle(DHE) = 106o
angle(AHB) and angle(DHE) are vertical angles ---> angle(DHE) = 106o