There is an equilateral triangle with points , and on lines , and respectively.
, and . If , and are connected to form a triangle and the side lengths of are 62 each, what is the area of to the nearest integer?
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It can be easily proved by congruence of triangles that all the small triangles are congruent to each-other.Therefore the triangle D E F is equilateral,although this is not important to our problem.It's not hard to find that F C = B E = A D = 3 1 2 4 and B D = E C = A F = 3 6 2 .Lets take a look at the small triangles which are congruent,these are A F D , F E C and B D E .We know that one of their sides is equal to 3 1 2 4 and the other one is 3 6 2 .We also know the angle between them is 6 0 degrees.Therefore there areas are easy to find using trigonometry. Let S represent the area of one of these triangles which are congruent.
S = 2 1 ∗ 3 1 2 4 ∗ 3 6 2 ∗ 2 3 because s i n 6 0 = 2 3 .Multiplying it by 3 we get the whole area of the small triangles which is 3 S = 1 2 1 2 4 ∗ 6 2 ∗ 3 .The area of the larger triangle A B C is equal to 4 3 8 4 4 ∗ 3 .If we substract the whole area of the smaller triangles from the areaa of the large we will get our desired result which is approximately 5 5 5