In the figure above, fi the area of the triangle on the right is twice the area of the triangle on the left, the in terms of s, S=
o ((sqrt2)/2)s
o ((sqrt3)/2)s
o (sqrt2)s
o (sqrt3)s
o 2s
I've attached a screen shot of the question. Not sure how they got the answer. Many Thanks in advance!
PowerPrep Exam 2 Question 12
This topic has expert replies
- jayhawk2001
- Community Manager
- Posts: 789
- Joined: Sun Jan 28, 2007 3:51 pm
- Location: Silicon valley, California
- Thanked: 30 times
- Followed by:1 members
Area of triangle given its sides a, b and c = sqrt [ s(s-a)(s-b)(s-c) ]
where s = (a+b+c) / 2
Now, consider a,b,c to be the sides of the smaller triangle and A,B,C to
be the sides of the larger triangle.
we know A/a = B/b = C/c (because they are proportional). Lets call this x
s1 = (a+b+c)/2
s2 = (A+B+C)/2
s2/s1 = x = A/a = B/b = C/c
We have
2 * sqrt [ s1(s1-a)(s1-b)(s1-c) ] = sqrt [ s2(s2-A)(s2-B)(s2-C) ]
2 * sqrt [ s1(s1-a)(s1-b)(s1-c) ] = sqrt [ x*s1 * x*(s1-a) *x*(s1-b) *x*(s1-c) ]
4 * s1(s1-a)(s1-b)(s1-c) = x^4 * s1(s1-a)(s1-b)(s1-c)
So, x = sqrt(2)
So, if smaller triangle has side s, the bigger one has S = sqrt(2) * s
Hence C
where s = (a+b+c) / 2
Now, consider a,b,c to be the sides of the smaller triangle and A,B,C to
be the sides of the larger triangle.
we know A/a = B/b = C/c (because they are proportional). Lets call this x
s1 = (a+b+c)/2
s2 = (A+B+C)/2
s2/s1 = x = A/a = B/b = C/c
We have
2 * sqrt [ s1(s1-a)(s1-b)(s1-c) ] = sqrt [ s2(s2-A)(s2-B)(s2-C) ]
2 * sqrt [ s1(s1-a)(s1-b)(s1-c) ] = sqrt [ x*s1 * x*(s1-a) *x*(s1-b) *x*(s1-c) ]
4 * s1(s1-a)(s1-b)(s1-c) = x^4 * s1(s1-a)(s1-b)(s1-c)
So, x = sqrt(2)
So, if smaller triangle has side s, the bigger one has S = sqrt(2) * s
Hence C