12.7
Using the Pythagorean theorem, you can easily calculate the length of BC.
So:
BC = sqrt(12^2 - 6^2) = sqrt(144 - 36) = sqrt(108) = 10.39230485
Now consider triangle BCD. You know all three angles and one side. Using the law of sines you know that ratio of the sine of each angle over the opposite side is constant. So:
BC/sin(55) = CD/sin(90)
BC/sin(55) = CD/sin(90)
sin(90)BC/sin(55) = CD
1*BC/sin(55) = CD
BC/sin(55) = CD
10.39230485/0.819152044 = CD
12.68666167 = CD
12.7 = CD
The expression is a perfect square trinomial if and only if c = 121.
<h3>
How to get the value of c?</h3>
A perfect square trinomial is written as:
(a + b)^2 = a^2 + b^2 + 2ab
In this case, we have:
t^2 - 22t + c
We can rewrite this as:
t^2 - 2*11*t + c
Then we have:
a = t
b = -11
And we will have that:
c = b^2 = (-11)^2 = 121
Then we have:
t^2 - 2*11*t + 121
Which is a perfect square trinomial:
(t - 11)^2 = t^2 - 22t + 121
Learn more about perfect squares:
brainly.com/question/1538726
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50 is the answer did I help u