geno3141

cos(A + B)  =  cosA·cosB - sinA·sinB

Angle A is in the second quadrant. Draw the diagram! Using the quadratic formula, the missing side has length 5. Because it's in the second quadrant, x = -5, y = 12, hypotenuse = 13. sinA = 12/13, cosA = -5/13

Angle B is in the fourth quadranta. Draw the diagram! Using the quadratic formula, the missing side has length 24. Because it in the fourth quadrant, x = 24, y = -7, hypotenuse = 25. sinB = -7/24, cosB = 24/25.

Place these values into the formula for cos(A + B) to get the answer.

(120 kg x m/min) x (1000 g / kg) x ( 100 cm / m ) x ( 1 min / 60 sec )  =  200 000 g x cm/s 

Are some of these exponents:  is a2 really a^2

And waht is b21?

Is 2(a-b)2b really 2(a-b)^2·b ?

Please post back.

In you are dealing with interest compounded continuously, use the formula:  A = Pe^(rt)  where:

A  =  final amount = 1,000,000        P = initial amount = 1,000     e = 2.718...

r = rate (as a decimal) = .08            t = number of years

1 000 000  =  1000 · e ^(.08 · t)                   divide by 1000          --->      1000 = e ^(.08 · t) 

Since your variable is an exponent, find the  ln  of both sides:       ln(1000)  =  ln( e ^(.08 · t) ) 

An exponent within a log comes out as a multiplier:                      ln(1000)  =  (.08 · t) · ln(e)

ln(e)  =  1                                                                                 ln(1000)  =  .08t

Divide by .08:                                                                                       t  =  86.3 yrs.  (approx)

A literal equation; that is, an equation that has only letters, representing variables and constants.

7^0  =  1    (Any number, except 0, to the 0 power is 1.)

7^-2  =  1 / 7²  =  1/49

1 + 1/49  =  1 1/49

Rearrange:  -2x - 4x + 7 - 1

Simplify  -2x - 4x  to get  -6x

Simplify  7 - 1  to get  6

=  -6x + 6

You can also use prove identities to prove other identities.

An identity is true for all values of the identity.

Although it is true that the graph of the left side of the identity must be the same as the graph of the right side of the identity, just looking won't be good enough (because you will be looking at only a restricted portion of the graph and graphs might look identical at one scale but might look different at a smaller scale.

The Associative Property for Addition is:  a + ( b + c )  = ( a + b ) + c.

If there were an Associative Property for Subtraction it would have this form:  a - ( b - c )  =  ( a - b ) - c.

The real numbers does not have an Associative Property for Subtraction because of the following counterexample (one of many):   2 - ( 3 - 5 )  ≠  ( 2 - 3 ) - 5

     2 - ( 3 - 5 )  =  2 - ( -2 )  =  2 + 2  =  4

     ( 2 - 3 ) - 5  =  (-1) - 5  =  -6                       and 4  ≠  -6

I'm not certain what Z represents; does it represent complex number? If so, translate the above into complex numbers for a counterexample.

The period of a cos function is 2π divided by the coefficient of the variable: for this problem you need to find the value of (2π) ÷ (2π/6)  =  (2π) · ( 6/(2π) ).

The period of sin is found the same way; the period of tan is  π divided by the coefficient.