Unknown lengths of triangle, known area and internal angles

In summary, to find the lengths of a right angled triangle when given the area and the ratio of the two non-hypotenuse sides, you can use the formula a= br and b= √(A/r) to solve for the lengths. This method involves finding the values of both a and b separately using the given information.
  • #1
tim9000
867
17

Homework Statement



I know the area of a right angled triangle, I also know the ratio of the two non-hypotenuse sides.
Is there anyway of finding the lengths?

Thanks!

Homework Equations



I don't think there are any like Area = 1/2abSinC

The Attempt at a Solution



I obviously know that tan of the ratio will give one angle, so I know the internal angles.

buggered if I know, it's 2:45am here.
 
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  • #2
tim9000 said:

Homework Statement



I know the area of a right angled triangle, I also know the ratio of the two non-hypotenuse sides.
Is there anyway of finding the lengths?

If the sides are [itex]a[/itex] and [itex]b[/itex] then you know that the area of the triangle is [itex]\frac12 ab[/itex].
 
  • #3
If you call the two legs a and b then the area is (1/2)ab= A so ab= 2A.
The ratio of the two sides is a/b= r so that a= br. Replace a in the first equation by that: ab= (br)b= rb^2= A so b^2= A/r. Solve for b, then solve for a.
 
  • #4
pasmith said:
If the sides are [itex]a[/itex] and [itex]b[/itex] then you know that the area of the triangle is [itex]\frac12 ab[/itex].

I DON'T know the sides, just the ratio of the sides (the gradient of the hypotenuse)
 
  • #5
HallsofIvy said:
If you call the two legs a and b then the area is (1/2)ab= A so ab= 2A.
The ratio of the two sides is a/b= r so that a= br. Replace a in the first equation by that: ab= (br)b= rb^2= A so b^2= A/r. Solve for b, then solve for a.

Wow, that's brilliant, thanks very much!
 

1. How do you find the missing side length of a triangle with known area and internal angles?

To find the missing side length of a triangle, you can use the formula A = 1/2 * b * h, where A is the area, b is the base length, and h is the height. You can also use trigonometric ratios (sin, cos, tan) to find the missing side length.

2. Can you find the missing side length of any triangle with only the area and internal angles known?

Yes, as long as you have at least one side length and the corresponding angle, you can use trigonometric ratios to find the missing side length. If you only have the area and internal angles, you may need to use the formula A = 1/2 * b * h to find the missing side length.

3. What if I have multiple missing side lengths and only the area and internal angles?

If you have multiple missing side lengths, you will need to use the formula A = 1/2 * b * h to find the missing side length. You may also need to use trigonometric ratios to find the remaining side lengths.

4. Is there a specific order in which I should find the missing side lengths?

It is recommended to start by finding the base length using the formula A = 1/2 * b * h. Then, use trigonometric ratios to find the remaining side lengths in any order.

5. Can I find the missing side length if I only know the area and one internal angle?

Yes, as long as you have at least one side length and the corresponding angle, you can use trigonometric ratios to find the missing side length. If you only have the area and one internal angle, you may need to use the formula A = 1/2 * b * h to find the missing side length.

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