Answer:
=
+ 
Step-by-step explanation:
To verify the identity:
sinx/1-cosx = cscx + cotx
we will follow the steps below;
We will take just the left-hand side and work it out to see if it is equal to the right-hand side
sinx/1-cosx
Multiply the numerator and denominator by 1 + cosx
That is;
= 
open the parenthesis on the right-hand side of the equation at the numerator and the denominator
sinx(1+cosx) = sinx + sinx cosx
(1-cosx)(1+cosx) = 1 - cos²x
Hence
= 
But 1- cos²x = sin²x
Hence we will replace 1- cos²x by sin²x
=
=
= 
=
+ 
=
+ 
=
+ 
=
+ 
Note that;
=
= 
The required percentage error when estimating the height of the building is 3.84%.
<h3>How to calculate the percent error?</h3>
Suppose the actual value and the estimated values after the measurement are obtained. Then we have:
Error = Actual value - Estimated value
Given that,
An estimate of the height, H meters, of a tall building can be found using the formula :
H = 3f + 15
where the building is f floors high.
f = 85
The real height of the building is 260 m.
H = 3f + 15
Put f = 85 in the above formula
H = 3(85) + 15
H = 270 m
Error,

So, the required percentage error is 3.84%.
Learn more about percentage error;
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To solve part a, do the following.
49.84-44.50=<span>5.34
5.34/44.50=x/100
after solving the proportion, x would be equal to 12.
To solve part b, do the following.
50+12=62
</span>To solve part c, do the following.
The amount of the tip is:
x/<span>57.50=62/100
which is </span><span>35.65
The total bill is:
35.65+</span>57.50=<span>93.15</span>
Step-by-step explanation:
personal- 347 ÷ 809 = 0.43%
lap top- 398 ÷ 809 = 0.49%
printer- 64 ÷ 809 = 0.08%