Derive this identity from the sum and difference formulas for cosine:

Mathematics

1 answer:

DiKsa [7]3 years ago

4 0

Step-by-step explanation:

½ [cos(a − b) − cos(a + b)]

Using sum and difference formulas:

½ [cos a cos b + sin a sin b − (cos a cos b − sin a sin b)]

Distribute the negative:

½ (cos a cos b + sin a sin b − cos a cos b + sin a sin b)

Combine like terms:

½ (2 sin a sin b)

Simplify:

sin a sin b

You might be interested in

4y = 42 - 3y Can you help me find y?

Lesechka [4]

4y = 42 - 3y

First, add '3y' to both of the sides.
$4y + 3y = 42$
Second, add '4y + 3y' to get '7y'.
$7y = 42$
Third, divide both sides by '7'.
$y = \frac{42}{7}$
Fourth, how many times does 7 go into 42? 42 ÷ 7 = '6'.
$y = 6$

Answer: y = 6

7 0

3 years ago

Read 2 more answers

Radical form. ooooooooooo

kenny6666 [7]

Answer:

by using Pythagoras law

h²=p²+b²

7²=4²+b²

b²=49-16

b=√33=5.744

third side is 5.744