Sketch a right triangle representing this situation. The length of the hypotenuse is 26 ft and the angle of elevation from ground to top of ladder is 65°. The "opposite side" is the reach of the ladder, which we'll call x.
Then:
opp
sin 65° = ----------
26 ft
or (26 ft)(sin 65°) = opp side = height off the ground of top of ladder.
Evaluating this, we get:
(26 ft)(0.906) = 23.56 ft, or, rounded off, 23.6 ft
The ladder reaches 23.6 ft up the side of the building.
