Polygon Diagonals. The number of diagonals in a polygon = n(n-3)/2, where n is the number of polygon sides. For a convex n-sided polygon, there are n vertices, and from each vertex you can draw n-3 diagonals, so the total number of diagonals that can be drawn is n(n-3).
Answer:
27 degrees
Step-by-step explanation:
The easy way is by remembering the formula (a-b)/2=c, where a is the larger angle, and b is the smallest angle. (90-36)/2=27.
The longer, more drawn out answer goes as follows. See the image to understand the notation I use:
- AOE + BOD + BOA + DOE = 360
- AOE + BOD = 90 + 36 = 126
- BOA + DOE = 360 - AOE - BOD = 234
- Since the sum of a triangle's angles is 180, ODE = (180 - DOE) / 2
- Likewise, OBA = (180 - BOA) / 2
- Since CDE is 180, CDO = 180 - ODE = 180 - (180 - DOE) / 2
- Likewise, CBA is 180, so CBO = 180 - OBA = 180 - (180 - BOA) / 2
- The interior angles of the irregular polygon CBOD add up to 360, so CBO + CDO + BOD + BCD = 360.
- Substituting what we already found, 180 - (180 - BOA)/2 + 180 - (180 - DOE)/2 + 36 + BCD = 360
- Cleaning it all up, we get 180 + (BOA + DOE)/2 + 36 + BCD = 360
- As we found in line 3, BOA + DOE = 234, so substituting that in, 180 + 117 + 36 + BCD = 360
- Finally, solving for BCD (360 - 36 - 117 - 180) we get our answer, 27
Note: The long drawn out method shown above is a way to derive the formula for the secant theorem. You do not need to use this method every time. Just remember, large angle minus small angle, all divided by 2. That is it.
9514 1404 393
Answer:
(c) BK = 65
Step-by-step explanation:
Corresponding sides are proportional in similar triangles, so ...
ZT/ZQ = KF/KB
27/(2x +7) = 45/(4x+1)
27(4x+1) = 45(2x +7) . . . cross-multiply
3(4x +1) = 5(2x +7) . . . . divide by 9
12x +3 = 10x +35 . . . . . eliminate parentheses
2x = 32 . . . . . . . . . . . . . subtract 10x+3
x = 16 . . . . . divide by 2
Then the length of BK is ...
BK = 4x+1 = 4·16 +1
BK = 65
Answer:
4
Step-by-step explanation:
2 + 2 = 4
In order to really understand this we need to break it down into simple terms.
Basically what we are doing here is adding two things together.
Put it like this, you have two fish, and you get another two fish, you now have four fish.
If you don't understand anything or need me to explain it better please don't hesitate to ask.