83 boxes are required to carry 800 books.
According to the question:
One Box can hold weight = 30 pounds
We know that , 1 pound= 0.45 kg
hence, 30 pounds = 30 x 0.45 = 13.5kg
hence, one box can carry 13.5 kg of weight.
Now,
Weight of 1 book = 1.4 kg
So, Total Weight of 800 books= 1.4 x 800 kg
And , No. of boxes required to carry 800 books = (1.4 x 800)/13.5 = 82.96
or approximately 83 boxes
Hence, 83 boxes are required to carry 800 books.
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Answer: see proof below
<u>Step-by-step explanation:</u>
Given: A + B + C = π and cos A = cos B · cos C
scratchwork:
A + B + C = π
A = π - (B + C)
cos A = cos [π - (B + C)] Apply cos
= - cos (B + C) Simplify
= -(cos B · cos C - sin B · sin C) Sum Identity
= sin B · sin C - cos B · cos C Simplify
cos B · cos C = sin B · sin C - cos B · cos C Substitution
2cos B · cos C = sin B · sin C Addition
Division
2 = tan B · tan C

<u>Proof LHS → RHS</u>
Given: A + B + C = π
Subtraction: A = π - (B + C)
Apply tan: tan A = tan(π - (B + C))
Simplify: = - tan (B + C)

Substitution: = -(tan B + tan C)/(1 - 2)
Simplify: = -(tan B + tan C)/-1
= tan B + tan C
LHS = RHS: tan B + tan C = tan B + tan C 
Answer: rational
a rational number is a number that can be expressed by a quotient or a fraction
Answer:
<h3>Angle 6 = 101°</h3><h3>Angle 5 = 79°</h3><h3>Angle 7 = 79</h3>
Step-by-step explanation:
Angle 6 will 101°
This is because we can see that Angle 4 is alternate interior angle to Angle 6 and alternate interior angles are always equal.
<h2>So angle 6 will be 101°</h2>
Angle 7 = 79°
Here we can see that Angle 6 and angle 7 are supplementary which means it has a measure of 180°
So the value of Angle 7 will be

<h2>Hence the measure of angle 7 will be 79°</h2>
Angle 5 = 79°
Angle 7 and Angle 5 is vertically opposite to each other and we know that vertically opposite angles are always equal so the measure will be 79°
<h3>Hence the measure of Angle 5 will be 79°</h3>
Answer:
1.False
2.False
3.True
4.True
5.not sure, it could be true or false because adjacent angles can add up to 180 or even 360 as long as they have the same vertex