Let's draw the scenario to better understand the details.
To be able to determine the height of the flagpole, let's create two different triangles with 29.5° and 39° 45' angle. The two triangles have one common base at 80 Feet, yet have different heights at H+h and H respectively.
Where,
H = Height of the library
h = Height of the flag
The two triangles are proportional at a common base, thus, let's generate this expression using the Law of Sines:
[tex]\frac{H+h}{\sin(39\degree45^{\prime})}\text{ = }\frac{H}{\sin(29.5^{\circ})}[/tex]Let's simplify,
[tex]\frac{H+h}{\sin(39\degree45^{\prime})}\text{ = }\frac{H}{\sin(29.5^{\circ})}\text{ }\rightarrow\text{ (}H+h)(\sin (29.5^{\circ}))\text{ = (H)(}\sin (39\degree45^{\prime}))[/tex][tex]H\sin (29.5^{\circ})\text{ + h}\sin (29.5^{\circ})\text{ = H}\sin (39\degree45^{\prime})\text{ ; but }29.5^{\circ}=29^{\circ}30^{\prime}[/tex][tex]H\sin (29^{\circ}30^{\prime})\text{ + h}\sin (29^{\circ}30^{\prime})\text{ = H}\sin (39\degree45^{\prime})[/tex][tex]\text{h}\sin (29^{\circ}30^{\prime})\text{ = H}\sin (39\degree45^{\prime})\text{ - }H\sin (29^{\circ}30^{\prime})[/tex][tex]\text{ h(}0.4924235601)\text{ = H(0.63943900198) -H}(0.4924235601)[/tex][tex]\text{ h(}0.4924235601)\text{ = H(0.14701544188)}[/tex][tex]undefined[/tex]
