The tangent line is perpendicular to the radius from the center of the circle to the point of tangency.
ΔDCE is similar to ΔDBA
DC/DB=DE/DA
15/50=DE/40
DE=12

3 0

3 years ago

A golfball is hit from the ground with an initial velocity of 200 ft/sec. The horizontal distance that the golfball will travel,

algol13

Answer:

The golfball launched with an initial velocity of 200ft/s will travel the maximum possible distance which is 1250 ft when it is hit at an angle of $\pi/4$ .

Step-by-step explanation:

The formula from the maximum distance of a projectile with initial height h=0, is:

$d(\theta)=\frac{v_i^2sin(2\theta)}{g}$

Where $v_i$ is the initial velocity.

In the closed interval method, the first step is to find the values of the function in the critical points in the interval which is $[0, \pi/2]$ . The critical points of the function are those who make $d'(\theta)=0$ :

$d(\theta)=\frac{v_i^2\sin(2\theta)}{g}\\d'(\theta)=\frac{v_i^2\cos(2\theta)}{g}*(2)\\d'(\theta)=\frac{2v_i^2\cos(2\theta)}{g}$

$d'(\theta)=0\\\frac{2v_i^2\cos(2\theta)}{g}=0\\\cos(2\theta)=0\\2\theta=\pi/2,3\pi/2,5\pi/2,...\\\theta=\pi/4,3\pi/4,5\pi/4,...$

The critical value inside the interval is $\pi/4$ .

$d(\theta)=\frac{v_i^2sin(2\theta)}{g}\\d(\pi/4)=\frac{v_i^2sin(2(\pi/4))}{g}\\d(\pi/4)=\frac{v_i^2sin(\pi/2)}{g}\\d(\pi/4)=\frac{v_i^2(1)}{g}\\d(\pi/4)=\frac{(200)^2}{32}\\d(\pi/4)=\frac{40000}{32}\\d(\pi/4)=1250ft$

The second step is to find the values of the function at the endpoints of the interval:

$d(\theta)=\frac{v_i^2sin(2\theta)}{g}\\\theta=0\\d(0)=\frac{v_i^2sin(2(0))}{g}\\d(0)=\frac{v_i^2(0)}{g}=0ft\\\theta=\pi/2\\d(\pi/2)=\frac{v_i^2sin(2(\pi/2))}{g}\\d(\pi/2)=\frac{v_i^2sin(\pi)}{g}\\d(\pi/2)=\frac{v_i^2(0)}{g}=0ft$

The biggest value of f is gived by $\pi/4$ , therefore $\pi/4$ is the absolute maximum.

In the context of the problem, the golfball launched with an initial velocity of 200ft/s will travel the maximum possible distance which is 1250 ft when it is hit at an angle of $\pi/4$ .

4 0

3 years ago

397 of 514 randomly selected U.S. adults interviewed said they would not be bothered if the National Security Agency collected r

Afina-wow [57]

Answer:

z=14.73

p=0.000

for 99% confidence level the null hypothesis is rejected, thus majority of us adults would not bothered if the NSA collected personal records.

Step-by-step explanation:

$H_{0}$ : Half of US adults would not bothered if the NSA collect records of personal telephone calls

$H_{A}$ : Majority of the adults would not bothered if the NSA collect records of personal telephone calls

According to the sample, z-value can be found using the formula:

z= $\frac{X-M}{\sqrt{n*p*(1-p)} }$ where

X is the adults, who would not be bothered in the survey (397)
M is the mean of the distribution of null hypothesis (257)
n is the sample size (514)
p is the proportion of the sample, who said they would not bothered ( $\frac{397}{514}$ ≈ 0.77)

Putting these numbers in the formula,

z=14.73 and corresponding p value is p≈0.000

Since p<0.01, for 99% confidence level we reject the null hypothesis, thus majority of us adults would not bothered if the NSA collected personal records.

8 0

3 years ago