D is mid point of BC.Therefor BD=DC=X/2. (18 / 3 = 6). 2.) An equilateral triangle is a triangle with all three sides equal and all three angles equal to 60°. To find the height of an equilateral triangle , follow these steps: 1.) Finding the Height of a Triangle. Also, does it matter which side you choose as your base? Theorm [ a^2+b^2=c^2] to find the length of that line, which is now the height. As the name suggests, ‘equi’ means Equal, an equilateral triangle is the one where all sides are equal and have an equal angle. A. If the perimeter of an equilateral triangle is 18 and its area is 15.6 square units, what is the measure of its height? After finding your height, substitute your values for base and height into the formula for area of a triangle to find the area. The diagram at the right shows when to use each of these formulas. The equilateral triangle ABC has X as its side. Find the length of height = bisector = median if given side ( L ) : height bisector and median of an equilateral triangle : = Digit 1 2 4 6 10 F Since this is an equilateral triangle and we know its perimeter is 18, we can figure out that each side has a length of 6. Let ABC be the equilateral triangle with AD as an altitude from A meeting BC at D. Then, D will be the midpoint of BC. Then use the Pythagreom (sp?) All three heights have the same length that may be calculated from: h = a * √3 / 2, where a is a side of the triangle The area of an equilateral triangle (S) is calculated from the following figure: We know that the area of a triangle is ½(base x height). To find the height we divide the triangle into two special 30 – 60 – 90 right triangles by drawing a line from one corner to the center of the opposite side. Applying Pythagoras theorem in right-angled triangle ABD, we get: Hence, the height of the given triangle is 6√3 cm. This segment will be the height, and will be opposite from one of the 60 degree angles and adjacent to a 30 degree angle. This will also cut your base in half. The internal angles of the equilateral triangle are also the same, that is, 60 degrees. To find the area of an equilateral triangle, you need to calculate the length of half the side length and substitute it into the Pythagorean theorem to find the height. if a perpendicular AD is drawn from A to side BC, then AD is the height. Example 1: If you are given altitude h and you want to calculate side a, then you need to use formula which connects h and a.. Place a line from the vertex to the base of the triangle forming two right triangles. In the equilateral triangle ABC of side «a»: ⇒ S = ½.a.h …. Area of equilateral triangle. Let us find its height. How to find the height of an equilateral triangle. You could also substitute it into sin60^@, cos30^@, tan30^@, or tan60^@ to find the height. 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