To answer this you need to multiply 20 by 20. this gives 400cm
or you can also square 20
The ODE is linear:


Multiplying both sides by
gives

Notice that the left side can be condensed as the derivative of a product:

Integrating both sides with respect to
yields


Since
,

so that

Using Pythagoras theorem
|AB|*2=|d/2|=(5*2)+12*2
AB*2=25+144
AB=13
D/2= r=6.5cm
tan¥=6.5/5
tan¥=1.3
¥=tan inverse of (1.3)
¥=52.43 degrees