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
Answer:
5.75
Step-by-step explanation:
First, find the area of the entire traingle using the formula bh/2.
18*9/2=81 cm^2
Then subtract the area of the smaller triangle within the larger one (white triangle). It has the same base but a height of only 4.
18*4/2=36 cm^2
81-36=45
Final answer: 45 cm^2
I believe it would be 1.667 (1 2/3) percent
