Recall that to get the x-intercepts, we set the f(x) = y = 0, thus
![\bf \stackrel{f(x)}{0}=-4cos\left(x-\frac{\pi }{2} \right)\implies 0=cos\left(x-\frac{\pi }{2} \right) \\\\\\ cos^{-1}(0)=cos^{-1}\left[ cos\left(x-\frac{\pi }{2} \right) \right]\implies cos^{-1}(0)=x-\cfrac{\pi }{2} \\\\\\ x-\cfrac{\pi }{2}= \begin{cases} \frac{\pi }{2}\\\\ \frac{3\pi }{2} \end{cases}](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7Bf%28x%29%7D%7B0%7D%3D-4cos%5Cleft%28x-%5Cfrac%7B%5Cpi%20%7D%7B2%7D%20%20%5Cright%29%5Cimplies%200%3Dcos%5Cleft%28x-%5Cfrac%7B%5Cpi%20%7D%7B2%7D%20%20%5Cright%29%0A%5C%5C%5C%5C%5C%5C%0Acos%5E%7B-1%7D%280%29%3Dcos%5E%7B-1%7D%5Cleft%5B%20cos%5Cleft%28x-%5Cfrac%7B%5Cpi%20%7D%7B2%7D%20%20%5Cright%29%20%5Cright%5D%5Cimplies%20cos%5E%7B-1%7D%280%29%3Dx-%5Ccfrac%7B%5Cpi%20%7D%7B2%7D%0A%5C%5C%5C%5C%5C%5C%0Ax-%5Ccfrac%7B%5Cpi%20%7D%7B2%7D%3D%0A%5Cbegin%7Bcases%7D%0A%5Cfrac%7B%5Cpi%20%7D%7B2%7D%5C%5C%5C%5C%0A%5Cfrac%7B3%5Cpi%20%7D%7B2%7D%0A%5Cend%7Bcases%7D)
Tan(58)=10/x
x=10/tan(58)
x= 6.2
2|3x + 5| = -10 . Divide both sides by 2:
|3x + 5| = -5 ===>3x+5=-5 & -3x-5=-5 In both cases x=0
Maximum speed: 55mph + 5mph = 60mph
minimum speed: 55mph - 5mph = 50mph
Hope this helped?
<h3>
Answer: 15 years old</h3>
=============================================
Explanation:
m = Maggie's age (some positive whole number)
4m = four times her age
4m-7 = seven years younger than 4m = brother's age
Add up her age (m) and her brother's age (4m-7) to get a sum of 68.
m+(4m-7) = 68
5m-7 = 68
5m = 68+7
5m = 75
m = 75/5
m = 15
Maggie is currently 15 years old.
Her brother is currently 4m-7 = 4*15-7 = 60-7 = 53 years old.
Their current year ages add to: 15+53 = 68 which confirms the answer.
