The height of an equilateral triangle is 10. Find its area divided by three at the root of the fractional bar three

Jimena Hatfield

Jimena Hatfield

Answered question

2022-09-12

The height of an equilateral triangle is 10. Find its area divided by three at the root of the fractional bar three

Answer & Explanation

Willie Gilmore

Willie Gilmore

Beginner2022-09-13Added 8 answers

S tr. = (a h) / 2, where h = height, and is the base of the triangle. (For an equilateral triangle, a is any side.)
We have h = 10 cm.
Let's find a. The triangle is equilateral by condition, the height divides it into 2 right-angled triangles, the hypotenuse of which is equal to a, one leg is the height h = 10 cm, and the other = a / 2, (since the height is both the bisector and the median).
According to the Pythagorean theorem: a 2 = h 2 + ( a / 2 ) 2 ; ( 4 a 2 ) / 4 = ( 4 h 2 + a 2 ) / 4 ;
4 a 2 a 2 = 4 h 2 , 3 a 2 = 4 h 2 ; a = 4 h 2 / 3 = 2 h / 3 ; a = 2 10 / 3 ( c m )
Let's find S. S = ( a h ) / 2 = ( 2 h / 3 ) h / 2 = h 2 / 3 ; S = 10 10 / 3 ( c m 2 )
Let's find S : ( 3 / 3 )
S : ( 3 / 3 ) = ( h 2 / 3 ) : ( 3 / 3 ) = ( h 2 3 ) / ( 3 3 ) = h 2 = 10 10 = 100 ( c m 2 )
Answer: S : ( 3 / 3 ) = 100 c m 2

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