Answer:
From the sum of angles on a straight line, given that the rotation of each triangle attached to the sides of the octagon is 45° as they move round the perimeter of the octagon, the angle a which is supplementary to the angle turned by the triangles must be 135 degrees
Step-by-step explanation:
Given that the triangles are eight in number we have;
1) (To simplify), we consider the five triangles on the left portion of the figure, starting from the bottom-most triangle which is inverted upside down
2) We note that to get to the topmost triangle which is upright , we count four triangles, which is four turns
3) Since the bottom-most triangle is upside down and the topmost triangle, we have made a turn of 180° to go from bottom to top
4) Therefore, the angle of each of the four turns we turned = 180°/4 = 45°
5) When we extend the side of the octagon that bounds the bottom-most triangle to the left to form a straight line, we see the 45° which is the angle formed between the base of the next triangle on the left and the straight line we drew
6) Knowing that the angles on a straight line sum to 180° we get interior angle in between the base of the next triangle on the left referred to above and the base of the bottom-most triangle as 180° - 45° = 135°.
The solution (x,y) needs to work in both equations. With multiple choice you can do guess and test method. Otherwise you need to combine the two equations into one by substitution or elimination methods.
21. substitution works well here since one equation is y= x+3. you can easily substitute the (x+3) for y in the other equation.
2x + (x+3) = -6
3x + 3 = -6
3x = -9
x = -3
use this in either equation to find y.
y = (-3)+3
solution: (-3,0)
22. these both equal y so they equal each other.
4x - 1 = 3x +6
4x - 3x = 6 + 1
x = 7
use this in either equation to find y
y = 4(7) - 1
y = 28 - 1
y = 27
solution: (7,27)
23. one equation is y = 2x - 3. So substitute (2x -3) for y in the other equation.
4x = 2(2x - 3) + 6
4x = 4x - 6 + 6
4x = 4x
x = x
any solution will work, infinitely many.
24. infinitely many solutions means the two equations are the same equation. Like the previous one they didn't look the same but if you put them both in terms of y...
y= 2x-3
4x = 2y + 6
4x - 6 = 2y
(4x - 6)/2 = y
2x - 3 = y
same equation.
from the image, I can't see all options but A & C do not look like the same equations. It's got to be either B or D.
12/30 = 18/45....cross multiply
(30)(18) = (12)(45)
540 = 540...proportional
another way to tell is to see if they are equivalent...because proportions are nothing but equivalent fractions.
12/30 = 2/5
18/45 = 2/5
so yes, they are proportional
Answer:
a this is because bigger negative numbers are smaller
