A and B are points on j.
C and D are points on k.
Join AD and BC.
ABCD is a quadrilateral.
Clearly, the quadrilateral ABCD is the only plane that contains the points A, B, C and D.
Hence, correct answer is option A. Exactly one.
Answer: see proof below
<u>Step-by-step explanation:</u>
Use the Double Angle Identity: sin 2Ф = 2sinФ · cosФ
Use the Sum/Difference Identities:
sin(α + β) = sinα · cosβ + cosα · sinβ
cos(α - β) = cosα · cosβ + sinα · sinβ
Use the Unit circle to evaluate: sin45 = cos45 = √2/2
Use the Double Angle Identities: sin2Ф = 2sinФ · cosФ
Use the Pythagorean Identity: cos²Ф + sin²Ф = 1
<u />
<u>Proof LHS → RHS</u>
LHS: 2sin(45 + 2A) · cos(45 - 2A)
Sum/Difference: 2 (sin45·cos2A + cos45·sin2A) (cos45·cos2A + sin45·sin2A)
Unit Circle: 2[(√2/2)cos2A + (√2/2)sin2A][(√2/2)cos2A +(√2/2)·sin2A)]
Expand: 2[(1/2)cos²2A + cos2A·sin2A + (1/2)sin²2A]
Distribute: cos²2A + 2cos2A·sin2A + sin²2A
Pythagorean Identity: 1 + 2cos2A·sin2A
Double Angle: 1 + sin4A
LHS = RHS: 1 + sin4A = 1 + sin4A 
Explanation:
Each box contains

The ratio that compares the number of blueberry bagels in one box to the number of onion bagels in one box will be calculated below as

This means that for every one onionbagels in the box, there are 2 blueberry bagels
Part B:
Given that there are 20 blueberry bagels, the number if onion bagels will be calculated below as

Hence,
The final answer is
Answer: d = 1/3
Step-by-step explanation: 48y = 48/4 = 12. So, 2d(18) is equal to 12. 12/18 is 2/3 so 2d has to equal 2/3. That means d = 1/3.
Answer
7 = -x
Step-by-step explanation:
18- 8x = 8 + 3(1 - 3x)
18- 8x = 8 +3-9x
18- 8x = 11 - 9x
7- 8x = -9x
7 = -x