Question 930566
<pre>
{{{drawing(400,200,-.5,1.5,-.5,.5,
locate(.4,.29,L),
line(0,0,cos(25*pi/180),sin(25*pi/180)),
red(arc(0,0,.4,-.4,0,25)), locate(.2,.095,"25°"),
line(cos(25*pi/180),0,cos(25*pi/180),sin(25*pi/180)),
locate(.92,.23,matrix(1,2,30,m)),
line(0,0,cos(25*pi/180),0) )}}}

The side opposite to the 25° angle is the 30 m rise.
The hypotenuse is the length of the ramp L.

Since {{{SINE=OPPOSITE/HYPOTENUSE}}}, we have the equation:

{{{sin("25°")}}}{{{""=""}}}{{{30/L}}}

Put 1 under the sin(25°)

{{{sin("25°")/1}}}{{{""=""}}}{{{30/L}}}

Now we can cross-multiply:

{{{L*sin("25°")}}}{{{""=""}}}{{{30}}}

Divide both sides by sin(25°):

{{{L}}}{{{""=""}}}{{{30/sin("25°")}}}

Get your calculator and get

{{{L}}}{{{""=""}}}{{{matrix(1,2,70.98604749,m)}}}

Round to as many decimal places as your 
teacher tells you to.

Edwin</pre>