SOLUTION: If one side of a triangle is x + 20 another is 2x - 20 the last one is 2x - 40 how do you work out the value of x? I have tried to work it out by showing my equation as 5x-40 but I

Algebra ->  Triangles -> SOLUTION: If one side of a triangle is x + 20 another is 2x - 20 the last one is 2x - 40 how do you work out the value of x? I have tried to work it out by showing my equation as 5x-40 but I      Log On


   

Question 956525: If one side of a triangle is x + 20 another is 2x - 20 the last one is 2x - 40 how do you work out the value of x? I have tried to work it out by showing my equation as 5x-40 but I don't know the next step of the formula. I was thinking of 5x-40=180 because I know there is 180 degrees in a triangle so minus it by 40 to get 140 then divide it by 5 to figure out what x is so... 28 but can you please make sure I have done it correctly?
Thanks.
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
The description tells very little about your triangle. You need more information or the description is lacking and no solution of x.

BUT you could test the three given expressions to see if they conform to Pythagorean Theorem. You may need to setup three equations to find out.

Are ANY one of these true?
-
%28x%2B20%29%5E2%2B%282x-20%29%5E2=%282x-40%29%5E2
-
%282x-20%29%5E2%2B%282x-40%29%5E2=%28x%2B20%29%5E2
-
%28x%2B20%29%5E2%2B%282x-40%29%5E2=%282x-20%29%5E2

If ONE of those is true, then the expressions for the sides are of a right triangle. You still cannot solve for x, but you could find the angle measures.

I have not worked through this any further, so how far you can go with this is uncertain.

AFTER-THOUGHT.
Triangle Inequality Theorem could give possible set of values for x. You would work from three inequality statements according to this theorem.

FROM PERSONAL COMMENT:
If the triangle is scalene, all you can do is use triangle-inequality theorem to solve for possible set of values for x. The problem description and question give nothing more to work with. What formula do you expect to use?