Answer: 
Step-by-step explanation:
According to the trigonometric identities we have the following formula:

Now, we have the following:

Where
and 
Hence:


Finally:

Answer: see proof below
<u>Step-by-step explanation:</u>
Use the Sum & Difference Identity: tan (A - B) = (tanA - tanB)/(1 + tanA tanB)
Use the Half-Angle Identity: tan (A/2) = (1 - cosA)/(sinA)
Use the Unit Circle to evaluate tan (π/4) = 1
Use Pythagorean Identity: cos²A + sin²A = 1
<u>Proof LHS → RHS</u>








= cos A
LHS = RHS: cos A = cos A 
Solution :
Here we can use the Binomial distribution, as there are only two possible outcomes.
The given data:
n = 150
q = 98%
= 0.98
p = probability of not finding relief = 1 - 0.98
= 0.02
A). The number of the individuals who do not find any relief from sinusitis is :
E(x) = np
= 150 x 0.02
= 3
B). The uncertainty of my estimate is = 

= 1.716