items for geometry

mathematics and geometry in particular, according to surveys of students, one of the most disliked the lessons, and all because they are forced to learn a huge number of formulas that are in the life of 90% of today's adults have not found practical application.But, for a moment, we learn the formula, solve problems, make the equation is not in order that they can come in handy in life, and because it develops thinking and logic.Even the ancient Greek sages say that human intelligence can be measured by the knowledge of mathematical sciences.And once you decide to become familiar with the use of formulas for an isosceles triangle - we take ourselves in hand and read the whole article.

pristupatk Before answering the question of how to find the area of ​​an isosceles triangle and move on to the practical part of the article, where the formulas and calculations, let us denote for themselves the very notion.Isosceles triangle - a triangle in which the equal length, two of the three parties, which are ca

lled side.In the case of the right triangle, where all sides are equal, he is also considered to be an isosceles triangle, but on the contrary, when they find an isosceles triangle right - wrong.

Parties should designate a triangle, do it this way, as shown in the picture below, where: A - sides, b-base, and h-height.

isosceles triangle

How to calculate the area of ​​an isosceles triangle formula.

Once we made designations height and angle of the sides, we can begin to address the problem.

To begin with, we define what we know.

If the height and base - that fit the classic formula (* - multiplication sign):

S = ½ * b * h

substitute, for example, the number, where: h = 16, b = 18, we get the following:

S = ½ * 18 * 16 * 16 = 9 = 144;

isosceles triangle area S = 144 cm2

There are other formulas that will help us how to find the area of ​​an isosceles triangle.One such formula is the method of Gerona.We will not write complex formulas take, as a basis, abbreviated:

S = ¼ b √4 * a2-b2

clear that b - base and - equal sides.The formula is suitable when the height h-known.

substitute values, let a = 6, b = 3, we get the following:

S = ¼ * 3 √4 * 62-32 = ¾ √144-9 = ¾ * 9 = 8,7

can be used tocalculate the area of ​​a side of the triangle and the angle between the parties:

mathematical formula

By sine table angle of 45 ° is equal to 0.7071, side and let it be equal to 6 cm, we get the following:

the overall result

As a result, the area of ​​an isosceles triangle is equal to12.6 cm2.

There are other ways to calculate the area, including in relation to an isosceles triangle, but they are quite complex, and do not apply to "elementary", the notion of a complex math calculations, such as the above.And talk about things that do not understand even the teachers with the experience - not worth it.

So you can breathe a sigh of relief at this small geometry course for finding the area of ​​an isosceles triangle will be considered as completed, and the knowledge gained from reading the article - lessons in the "five".