Elitmus
Exam
Numerical Ability
Geometry
there is a equilateral triangle whose area is A.another triangle is formed by joining the mid points.this process is continued.find the sum of these areas.
Read Solution (Total 4)
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- Area of equilateral triangle =(root(3)/4)*a^2=A(given)
side of triangle=a
now side is a/2
then total area A+A/4 +A/16-------
A/1-(1/4)=A*4/3 is total area - 9 years agoHelpfull: Yes(19) No(0)
- Ans:- the answer is 4
Explanation:- Area of Equilateral triangle formed by joining the mid point of an equilateral triangle is 1/4 th of the original triangle .
So this will form an infinite GP series with common ratio 1/4 and first term =3
So the Sum will be
3/(1-1/4)=4 - 9 years agoHelpfull: Yes(5) No(10)
- let the area of the eqilateral tringle=A
so, the area of the tringle joining the mid point of the sides=1/4A
and this process is continued.......... means tends to infinity..
so, this is geometry progression with infinite terms.....
A+1/4 A+1/16 A+...............infinite terms
whose first term a=A
common ratio r= 1/4
Now we can use the formula of the geometry progression s= a/(1-r)
putting the value in this equation we get ,
A/(1-1/4)
= 4/3 A is the right ans - 9 years agoHelpfull: Yes(2) No(0)
- Let ABC is an equilateral triangle with area = A
Remember: The area of the triangle formed when mid points of the triangle is joined is exactly one-fourth of the bigger triangle. So Area of DEF = A/4. Similarly Area of GHI = A/16 and so on ...
So Sum of the areas of all triangles = A+A/4+A/16+... ⇒A(1+1/4+1/16+...)
The series in the bracket is G.P. and S∞=a/1−r
⇒A(1/1−1/4⎞⎠⇒ ⇒4A/3 - 9 years agoHelpfull: Yes(1) No(0)
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