1: The smaller square in the figure below has a perimeter of 4 cm, and the larger square has an area of 16 cm^2. What is the distance from point A to point B? Express your answer as a decimal to the nearest tenth.
2: In the diagram, triangle ABE, triangle BCE and triangle CDE are right-angled, with angle AEB = angle BEC = angle CED = 60 degrees, and AE=24.
Find the perimeter of quadrilateral ABCD.
Thanks for all the help!
1.
The side of the smaller square = 1 cm and the side of the larger square = 4 cm
Let the distance from the top right of the smaller square to the intersection of AB with the side of the larger square = x
So the small triangle formed above the smaller square has a hypotenuse of √[ 1 + x^2]
And the larger triangle formed at the "top" part of the larger square has legs of 4 and [ (4) - (1 + x)] = (3 -x) so the hypotenuse of this triangle is √ [ 4^2 + (3 - x)^2 ] =
√ [ 16 + 9 - 6x + x^2 ] = √ [ x^2 - 6x + 25 ]
And the triangles are similar such that
1 / √[ 1 + x^2] = 4 / √ [ x^2 - 6x + 25 ] cross-multiply
√ [ x^2 - 6x + 25 ] = 4 √[ 1 + x^2] square both sides
x^2 - 6x + 25 = 16 (x^2 + 1)
x^2 - 6x + 25 = 16x^2 + 16
15x^2 + 6x - 9 = 0
5x^2 + 2x - 3 = 0
(5x - 3) (x + 1) = 0
Setting each factor to 0 and solving for x produces x = 3/5 = .6 and x = -1
But x is a length so it can't be negative
So x = 3/5 cm = .6cm
So....the length of AB is
√[ 1 + (.6)^2] + √ [ (.6)^2 - 6(.6) + 25 ] =
√ [ 1.36] + √ [ 21.76 ] ≈ 5.8 cm
2. We can find AB thusly
sin (60) = AB / 24
24 * √3 /2 = AB
12√3 = AB
And BE = (1/2) of AE = 12
But ABE and BCE form similar triangles
So....if BE is (1/2) of AE
Then BC is (1/2) of AB = 6√3
And CE is 1/2 of BE = 6
And triangle DCE is similar to triangle CBE
So since CE is (1/2) of BE....then...
ED is(1/2) of CE = 3 and
DC is (1/2) BC = 3√3
So the perimeter of ABCD =
AB + BC + CD + DE + EA =
12√3 + 6√3 + 3√3 + 3 + 24 =
[ 21√3 + 27 ] cm ≈ 63.4 cm
If I haven't made any errors !!!!
First one: slightly different approach...see diagram the 1's and 4's were given in the question for the squares,