A cross-section <span>is the intersection of a solid and a plane.
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Assuming the house is parallel to the ground, your triangle is made up by the house, the ground, and the ladder. Using sin(x) = opposite/hypotenuse on the angle 70 degrees, you would have sin(70) = 20/x (because 20 is the side opposite of the angle connecting the ladder and the ground)
--> simplify sin(70) * x = 20 --> x = 20 / sin(70
--> substitute (and make sure your calculator in in degrees) x= 21. 284
First you need to find the percent equivalent to that of the ratio. The ratio is 3:5. From there you would take the 3, and divide it by 5. 3/5=0.6. Apply that to the information that you are given: 8(0.6)=4.8.