In an equilateral triangle, another equilateral triangle is drawn insi...
Let the length of side of first equilateral triangle = x;
As shown in the figure, when an equilateral triangle is drawn inside another equilateral triangle joining the mid-points of the sides, the sides of that triangle will be half of the side of the 1st equilateral triangle;
In this way;
Side of 2
nd triangle = x/2;
Side of 3
rd triangle = x/4;
Side of 4
th triangle = x/8;
Side of 5
th triangle = x/16;
Side of 6
th triangle = x/32;
Side of 7
th triangle = x/64;
∴ Ratio of the area of 4
th to 7
th triangle = [√3/4 × (x/8)
2] : [√3/4 × (x/64)
2] = 64 : 1
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In an equilateral triangle, another equilateral triangle is drawn insi...
Problem:
In an equilateral triangle, another equilateral triangle is drawn inside joining the mid-points of the sides of the given equilateral triangle and the process continues up to seven times. What is the ratio of the area of the fourth triangle to that of the seventh triangle?
Solution:
Step 1: Identify the given information
- We have an equilateral triangle.
- Another equilateral triangle is drawn inside it by joining the midpoints of the sides.
- This process is repeated up to seven times.
Step 2: Understand the problem
- We need to find the ratio of the area of the fourth triangle to that of the seventh triangle.
Step 3: Visualize the triangles
- Let's label the vertices of the outer equilateral triangle as A, B, and C.
- The midpoints of the sides of the outer triangle form another equilateral triangle inside, which we will label as P, Q, and R.
- Similarly, we can label the midpoints of the sides of each subsequent triangle as follows:
- 2nd triangle: D, E, and F
- 3rd triangle: G, H, and I
- 4th triangle: J, K, and L
- 5th triangle: M, N, and O
- 6th triangle: X, Y, and Z
- 7th triangle: W, V, and U
Step 4: Observe the pattern
- By observing the pattern, we can see that each triangle formed is similar to the outer equilateral triangle.
- The ratio of the sides of each triangle to the previous triangle is 1:2.
- Therefore, the ratio of the areas of each triangle to the previous triangle is (1:2)^2 = 1:4.
Step 5: Calculate the ratio
- The ratio of the area of the fourth triangle (J, K, L) to that of the seventh triangle (W, V, U) is (1:4)^3 = 1:64.
Step 6: Choose the correct option
- The correct answer is option 'c': 64:1.