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 subtraction property of equality: if we subtract one side of the equation then we also must subtract from the other side of the equation.
The division property of equality: if we divide one side of the equation by a number then we also must divide the other side by the same number.
For this equation:
3 x + 5 = 26
3 x + 5 - 5 = 26 - 5 ( the Subtraction Property of Equality )
3 x = 21
3 x : 3 = 21 : 3 ( the Division Property of Equality )
x = 7
Answer: C ) The standard method for solving an equation like 3 x + 5 = 26 is to use the Subtraction Property of Equality and then the Division Property of Equality.
1 is 25
2 is 7.42
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