Convert. 5 days = lao hours

Eddie built the ramp shown to train his puppy to do tricks. What is the surface area of the ramp. The dimensions are 20,20,20,23

mamaluj [8]

Answer:

3775 in²

Step-by-step explanation:

The surface area of the ramp :

Area of rectangle = 20 * 23 = 460 in²

Area of rectangle = 25 * 23 = 575 in²

Bottom rectangle = 60 * 23 = 1380 in²

For the trapezium: (front and rear)

1/2 (base 1 + base 2) * height

Base total = 20+ 20+ 20= 60

1/2(60)*15 = 450 in²

Total surface Area :

(460 + 460 + 575 + 1380 + 450 + 450) in² = 3775 in²

6 0

3 years ago

Write -3+4i in the form r(cosx+isinx)

Zanzabum

$-3+4i$ is a complex number that satisfies

$\begin{cases}r\cos x=-3\\[1ex]r\sin x=4\\[1ex]r=\sqrt{(-3)^2+4^2}\end{cases}$

The last equation immediately tells you that $r=5$ .

So you have

$\begin{cases}\cos x=-\dfrac35\\[1ex]\sin x=\dfrac45\end{cases}$

Dividing the second equation by the first, you end up with

$\dfrac{\sin x}{\cos x}=\tan x=\dfrac{\dfrac45}{-\dfrac35}=-\dfrac43$

Because the argument's cosine is negative and its sine is positive, you know that $\dfrac\pi2$ . This is important to know because it's only the case that $y=\tan x\implies \arctan y=x$ whenever $-\dfrac\pi2$ . The inverse doesn't exist otherwise.

However, you can restrict the domain of the tangent function so that an inverse can be defined. By shifting the argument of tangent by $\pi$ , we have

$\tan(x-\pi)=y\implies x=\pi+\arctan y$

All this to say

$\tan x=-\dfrac43\implies x=\pi+\arctan\left(-\dfrac43\right)\approx2.2143\text{ rad}\approx126.9^\circ$

So, $-3+4i=5(\cos126.9^\circ+i\sin126.9^\circ)$ .