I know point a=1 But the others not sure
Answer:
B. 
Step-by-step explanation:
Let l represent length of rectangle and w represent width of rectangle.
We have been given four formulas for the perimeter of rectangle. We are asked to choose the formula that displays a common student error for finding the perimeter.
We know that perimeter of a polygon is sum of all sides of the polygon. We also know that rectangle is polygon having two sets of equal sides.
The perimeter, P, of rectangle will be sum of its all sides that is:

Combine like terms:

Factor out 2:

Upon looking at our given choices, we can see that formula represented by option B displays a common student error for finding the perimeter.
The value of x is 21√2/2
The correct option is (A)
<h3>What is Trigonometry?</h3>
Trigonometry is a branch of mathematics that studies relationships between the sides and angles of triangles.
In triangle having angle 60.
sin 60 = P/ 7√3
√3/2= P/7√3
2P= 21
P= 21/2
Now again
cos 45= 21/2/x
1/√2 = 10.5/x
x= 21√2/2
Learn more about trigonometry here:
brainly.com/question/26719838
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Answer:
7.9
Step-by-step explanation:
Answer: 2
Step-by-step explanation:
The product of 4*4= 16
The product of 4+4= 8
The quotient of 16÷8=2
Hope this helps