Derive these identities using the addition or subtraction formulas for sine or cosine:

a. sin a sin b = 1 / 2 (cos (a - b) - cos (a + b))

b. sin a cos b = 1 / 2 (sin (a + b) + sin (a - b))

Which is a better buy 13 and 10 or 18 and 15

What is the degree of x^4-3x+2 A. 3 B. 2 C. 4 D. 5

Evelyn walks on a treadmill for at least 1 hour but not more than 2 hours. She walks at an average rate of 3.5 miles per hour. The distance Evelyn walks in t hours is represented by a function. r (t) = 3.

In how many months were there more than two days with thunderstorms?

Determine how long it will take an object to rotate through 20.0 revolutions at an angular velocity of 2.8 radians per second. Use π=3.14. Round the answer to the nearest tenth.

Measure of a verticle angle is 7x+182 and another angle is 9x+194 solve for x

What are the first six nonzero multiples 5

How do you write 782% as a fraction or mixed number in simplest form?

Angelina spend $50 on 16 packages of cookies for her club members. sugar cookies cost $2.50 per package and chocolate chip cookies cost $3.50 per package. how many packages of each cookie does Angelina buy?

What are solutions to the equation below x^2 + 3x-18=0