Answer:
37°
Step-by-step explanation:
Here it is given that there are two flagpoles which are 20 m apart. One of them is 12m high and the other is 27m high .And we are interested in finding the angle of depression from the top of taller pole to the top of shorter pole .
For illustration, refer to the attachment or below ,
Illustration :-
[tex]\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\put(0,0){\line(0,1){6}}\put(0,0){\line(1,0){4}}\put(4,0){\line(0,1){4}}\multiput(0,4)(0.6,0){7}{\qbezier(0,0)(0,0)(0.5,0)}\qbezier(0,6)(0,6)(4,4)\put(0,6){\vector(1,0){3}}\qbezier(0.8,6)(1,5.8)(0.6,5.7)\put(1,5.6){$\theta$}\qbezier(3.2,4.42)(3,4.1)(3.25,4)\put(2.4,4.15){$\theta$}\put(-0.5,-0.5){A}\put(-0.5,6){E}\put(-0.5,3.8){D}\put(-0.8,5){15m}\put(4.3,-0.5){B}\put(-1.2,2){$ 27m $}\put(3.2,6){$ F $}\put(4.5,2){$ 12m $}\put(4.3,3.8){C}\put(-1,1.8){\vector(0,-1){1.8}}\put(-1,2.4){\vector(0,1){3.7}}\put(2,-0.5){$ 20m$}\put(2,3.5){$ 20m$}\end{picture} [/tex]
Here the angle of depression will be ,
[tex]\longrightarrow\sf \angle_{of \ depression}=\angle FEC [/tex]
Also ,
[tex]\sf\longrightarrow \angle FEC =\angle ECD \ (alternate \ interior \ angles)[/tex]
Let ,
[tex]\sf\longrightarrow \angle FEC =\angle ECD = \theta \ ( say ) [/tex]
Now in ∆ EDC , we have;
[tex]\sf\longrightarrow tan\theta =\dfrac{perpendicular}{base}\\ [/tex]
[tex]\sf\longrightarrow tan\theta =\dfrac{15m}{20m}\\[/tex]
[tex]\sf\longrightarrow tan\theta =\dfrac{3}{4}\\ [/tex]
[tex]\sf\longrightarrow \theta =tan^{-1}\bigg\lgroup \dfrac{3}{4}\bigg\rgroup\\ [/tex]
[tex]\sf\longrightarrow \underline{\boxed{\textsf{\textbf{$\boldsymbol{\theta}$= 37$^{\bf o }$ }}}} [/tex]
And we are done!
