The sides of a triangle are in the ratio 2:4 The length of the longest side of the triangle is 15 cm. Work out the perimeter of the triangle (will give brainliest)

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Step-by-step explanation:

yu should know

The first thing you need to do simplify the square roots and plot the figure. Now that the figure is plotted, it would be convenient to write down the coordinates with the corresponding letters. Now you have to dilate the figure. Take the coordinates of A (4, 6.93) and dilate the points by 2/5 (40% in a fraction because it is decreasing). So (x, y) will go to (2/5x, 2/5y). This is your new coordinate point. Repeat for all the other points. Since you need to find the perimeter, you need to use the distance formula, which is the square root of x1-y1 + x2-y2. Because you have a lot of points to calculate, I recommend using a distance formula calculator like http://www.mathwarehouse.com/calculators/distance-formula-calculator.php. Label the distance to all the sides once you figure it out with the calculator. Then, add it all up and you have the answer. 
I hope this helps. I just finished this in my extra summer school, so I understand the geometry pain. Good luck!