A quadrilateral is any figure with 4 sides, no matter what the lengths of
the sides or the sizes of the angles are ... just as long as it has four straight
sides that meet and close it up.
Once you start imposing some special requirements on the lengths of
the sides, or their relationship to each other, or the size of the angles,
you start making special kinds of quadrilaterals, that have special names.
The simplest requirement of all is that there must be one pair of sides that
are parallel to each other. That makes a quadrilateral called a 'trapezoid'.
That's why a quadrilateral is not always a trapezoid.
Here are some other, more strict requirements, that make other special
quadrilaterals:
-- Two pairs of parallel sides . . . . 'parallelogram'
-- Two pairs of parallel sides
AND all angles the same size . . . . 'rectangle'
(also a special kind of parallelogram)
-- Two pairs of parallel sides
AND all sides the same length . . . 'rhombus'
(also a special kind of parallelogram)
-- Two pairs of parallel sides
AND all sides the same length
AND all angles the same size . . . . 'square'.
(also a special kind of parallelogram, rectangle, and rhombus)
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)
Answer:
x=y[base side of isosceles triangle]
x²+y²=19²
x=√{19²/2)}
x=13.44
y=13.44
Answer:
Her speed is of 2 miles per hour.
Step-by-step explanation:
Velocity:
The velocity is given by the following formula:
In which v is the velocity, d is the distance and t is the time.
2/3 mile in 1/3 hour .
This means that 
Which unit rate describes antoinettes speed in miles per hour?
This is v. So
Her speed is of 2 miles per hour.
Answer: 1,259 meters.
Step-by-step explanation:
GIven: The highest elevation in a small country occurs on a mountain above sea level = 1,232 meter
The lowest elevation in the same country occurs below sea level = -27 meters
The difference in elevation between the highest and lowest points = Highest - lowest
= 1232 - (-27) meters
= 1232+27 meters [ (-)(-)=(+) ]
= 1259 meters
Hence, the difference in elevation between the highest and lowest points = 1,259 meters.
