Answer:
see explanation
Step-by-step explanation:
Using the double angle identity for sine
sin2x = 2sinxcosx
Consider left side
cos20°cos40°cos80°
= 
(2sin20°cos20°)cos40°cos80°
= 
(2sin40°cos40°)cos80°
= (sin80°cos80° )
= 
(2sin80°cos80° )
= . sin160°
= . sin(180 - 20)°
= . sin20°
= 
= right side , thus proven
Answer:
We have the function:
r = -3 + 4*cos(θ)
And we want to find the value of θ where we have the maximum value of r.
For this, we can see that the cosine function has a positive coeficient, so when the cosine function has a maximum, also does the value of r.
We know that the meaximum value of the cosine is 1, and it happens when:
θ = 2n*pi, for any integer value of n.
Then the answer is θ = 2n*pi, in this point we have:
r = -3 + 4*cos (2n*pi) = -3 + 4 = 1
The maximum value of r is 7
(while you may have a biger, in magnitude, value for r if you select the negative solutions for the cosine, you need to remember that the radius must be always a positive number)
Start with
Expand both parentheses by multiplying both terms by the number outside:
Sum like terms:
Simplify the "+3" on both sides:
Subtract 2x from both sides:
Divide both sides by 2:
For the equation:
-1=5 x^2 - 2 x
5 x^2 - 2 x + 1 = 0, then we substitute: a=5, b=-2, c =1
to discriminant formula: D= b^2 - 4 a c = (-2)^2 - 4 * 5 * 1 = 4 - 20 = - 16
Answer:
The discriminant is equal to -16 which means the equation has no real number solutions.
Answer:
Haeather ran at a speed of 5 miles per hour.
Step-by-step explanation:
Given that last week at the park Haeather ran 4 miles in 48 minutes, to determine what was Haeather rate of speed in miles per hour the following mathematical calculation must be performed:
48/4 = 12
Thus, Haeather ran 1 mile every 12 minutes.
60/12 = 5
1 x 5 = 5
Therefore, Haeather ran at a speed of 5 miles per hour.
