Построить 12 и 5 угольник со стороной 4 см; найти их внутренние углы, площадь, периметр. 20 баллов
1 answer:
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The tan(-x) is the same thing as -tan(x). The tangent function is also the same thing as sin(x)/cos(x), right? So let's rewrite that tan in terms of sin and cos:
![[cos(x)][tan(-x)]](https://tex.z-dn.net/?f=%5Bcos%28x%29%5D%5Btan%28-x%29%5D)
is the same as ![[cos(x)][ -\frac{sin(x)}{cos(x)}]](https://tex.z-dn.net/?f=%5Bcos%28x%29%5D%5B%20-%5Cfrac%7Bsin%28x%29%7D%7Bcos%28x%29%7D%5D%20)
We can now cancel out the cos(x), which leaves us only with -sin(x) remaining. So your answer is A.
We can now cancel out the cos(x), which leaves us only with -sin(x) remaining. So your answer is A.
Answer:
x = - 1 ± 2i
Step-by-step explanation:
we can use the discriminant b² - 4ac to determine the nature of the roots
• If b² - 4ac > , roots are real and distinct
• If b² - 4ac = 0, roots are real and equal
• If b² - ac < 0, roots are not real
for x² + 2x + 5 = 0
with a = 1, b = 2 and c = 5, then
b² - 4ac = 2² - (4 × 1 × 5 ) = 4 - 20 = - 16
since b² - 4ac < 0 there are 2 complex roots
using the quadratic formula to calculate the roots
x = ( - 2 ± ) / 2
= (- 2 ± 4i ) / 2 = - 1 ± 2i