If angle a measures 90 degrees and angles b and c measure 45 degrees and side ac measures 12 ft, find the length of side bc. explain.

a) 12 feet
b) 24 feet
c) 12√3 feet
d) 12√2 feet

Since the angle are both 45 degrees, then you know that both legs are equal=12.  
so to find the hypotenuse, you use the pythagorean theorem:

12^2+12^2= c^2
144+144=c^2
288=c^2
square root(144) x square root (2)=c
12 square root 2 is the answer, so D.

The answer is, the streetlight is 18 inches tall.