How to calculate leg length

How to calculate leg length

The rectangular triangle has two legs and a hypotenuse. Their values are interconnected among themselves. It means that knowing any two from these parameters, it is possible to calculate the third.


1. Rectangular triangle is called a triangle which has one right angle, and all others - sharp. All rectangular triangles have two legs. Isosceles triangles have two legs, equal on length, and two identical corners. Both of them are equal to 45 degrees. One of corners is equal in a simple (not isosceles) rectangular triangle 30 °, and another - 60 °. Each of legs can be found or on length of a hypotenuse and the remained leg, or on corners.

2. The essence of the first way of calculation of the boat consists in use of Pythagorean theorem. If the hypotenuse and one of legs is given, find the second for a formula: a= √ with²-b².

3. If in a task the isosceles rectangular triangle and a hypotenuse is given, it is necessary to resort to use of trigonometrical functions. One corner at such triangle is equal 90 °, and remained two - 45 °. Find legs of an isosceles triangle on the following formula:: to a=b=c*cosα=c*sinα.

4. At not isosceles rectangular triangle the leg is in a bit different way. The first corner of this figure is equal 90 °, the second - 60 °, and the third - 30 °. The final type of a formula depends on what leg is required to be found. If the smaller leg is unknown, it will be equal to the work of a hypotenuse on a cosine of a bigger corner: a=c*cos60 °. In this case find the second leg the following method: b=c*sin 60 °=c*cos30 °.

5. Besides, if one of corners equal 30 °, and one leg is given by a length, the second leg can be calculated on a formula of tangents. The formula for calculation of a leg is given below: tgα=a/b=tg 30 °=a/b. Respectively, the leg of an is equal: a=b*tg α.

Author: «MirrorInfo» Dream Team