SOLUTION: For questions 1 through 3, let sin(a) = 4/5 cos(b) = -8/17 1. Find sin(a + b) 2. Find cos(2a) 3. Find cos(b/2) given pi/2 < b

SOLUTION: For questions 1 through 3, let sin(a) = 4/5 cos(b) = -8/17 1. Find sin(a + b) 2. Find cos(2a) 3. Find cos(b/2) given pi/2 < b < pi 4.Find sin(tan^-1(x) + sin^-1 (3/5))

Question 1142401: For questions 1 through 3, let sin(a) = 4/5 cos(b) = -8/17
1. Find sin(a + b)
2. Find cos(2a)
3. Find cos(b/2) given pi/2 < b < pi
4.Find sin(tan^-1(x) + sin^-1 (3/5))
Answer by ikleyn(52817)   (Show Source): You can put this solution on YOUR website!
.

There is NO ENOUGH data in the post to find the answers to n1 and n2 by an unique way.

It requires additional information : we should know to which quadrants the angles "a" and "b" do belong.

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To see similar solved problems on calculating trig functions, look into the lessons
    - Calculating trigonometric functions of angles
    - Advanced problems on calculating trigonometric functions of angles
    - Evaluating trigonometric expressions
in this site.

Also, you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Trigonometry: Solved problems".

Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.

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