Answer:
Step-by-step explanation:
By the Pythagorean theorem, triangle BCD has
and triangle ABD has
.
Substituting the first equation into the second equation for 
gives the equation
Now triangle ABC has
Expanding out the left side, 
.
Now substitute the equation from before, 
, into the new equation.
We work to isolate 
by adding 
to both sides of equation and subtracting 
from both sides.
Divide both sides by 2 and you get 
Assume that x is positive and square root both sides to get the final result of
Answer:
y = x-1
Step-by-step explanation:
First step is to find the slope
Take two points on the line (1,0) and (2,1)
m = (y2-y1)/(x2-x1)
= (1-0)/(2-1)
= 1/1
The slope is 1
The y intercept ( where it crosses the y axis is -1)
The slope intercept form of the line is
y = mx+b where m is the slope and b is the y intercept
y = 1x-1
y = x-1
Answer:
cos 78⁰.
Step-by-step explanation:
Use cos 2A = cos^2 A - sin^2 A
so cos^2 39 - sin^2 39 = cos (2*39) = cos 78.
Check the picture below.
the "lateral" area, or "sides" area, is just the area of all the four triangular faces, and it doesn't include the bottom or base of the pyramid.
however, notice, each triangular face is really just a triangle with a base of 24, and a height of 16.
![\bf \left[\frac{1}{2}(\stackrel{b}{24})(\stackrel{h}{16}) \right]+\left[\frac{1}{2}(\stackrel{b}{24})(\stackrel{h}{16}) \right]+\left[\frac{1}{2}(\stackrel{b}{24})(\stackrel{h}{16}) \right]+\left[\frac{1}{2}(\stackrel{b}{24})(\stackrel{h}{16}) \right] \\\\\\ \textit{or just }\qquad 4\left[\frac{1}{2}(\stackrel{b}{24})(\stackrel{h}{16}) \right]\impliedby \textit{lateral area of the pyramid}](https://tex.z-dn.net/?f=%5Cbf%20%5Cleft%5B%5Cfrac%7B1%7D%7B2%7D%28%5Cstackrel%7Bb%7D%7B24%7D%29%28%5Cstackrel%7Bh%7D%7B16%7D%29%20%5Cright%5D%2B%5Cleft%5B%5Cfrac%7B1%7D%7B2%7D%28%5Cstackrel%7Bb%7D%7B24%7D%29%28%5Cstackrel%7Bh%7D%7B16%7D%29%20%5Cright%5D%2B%5Cleft%5B%5Cfrac%7B1%7D%7B2%7D%28%5Cstackrel%7Bb%7D%7B24%7D%29%28%5Cstackrel%7Bh%7D%7B16%7D%29%20%5Cright%5D%2B%5Cleft%5B%5Cfrac%7B1%7D%7B2%7D%28%5Cstackrel%7Bb%7D%7B24%7D%29%28%5Cstackrel%7Bh%7D%7B16%7D%29%20%5Cright%5D%0A%5C%5C%5C%5C%5C%5C%0A%5Ctextit%7Bor%20just%20%7D%5Cqquad%204%5Cleft%5B%5Cfrac%7B1%7D%7B2%7D%28%5Cstackrel%7Bb%7D%7B24%7D%29%28%5Cstackrel%7Bh%7D%7B16%7D%29%20%5Cright%5D%5Cimpliedby%20%5Ctextit%7Blateral%20area%20of%20the%20pyramid%7D)
