Please answer quickly Given: sin(A) = 4/5, pi/2 < A < pi and sin(B) = -2root5/5, pi < B < 3pi/2 What is the value of cos(A – B)?

-√5/5

Step-by-step explanation:

Given the following

sin(A) = 4/5

sinB - -2√5/5

SinA = 4/5 = opp/hyp

We can get cosA

opposite = 4

hypotenuse = 5

Adj = √5²-4² (pythagoras theorem)

Adj = √25-16

Adj = √9

Adj = 3

Cos A = Adj/hyp

Cos A = 3/5

Also

Sin B = -2√5/5 = opp/hyp

opposite = -2√5

hypotenuse = 5

Adj = √5²-(2√5)² (pythagoras theorem)

Adj = √25-20

Adj = √5

Cos B = Adj/hyp

Cos B =  √5/5

Evaluate cos (A-B)

cos (A-B) = cosAcosB + sinAsinB

cos (A-B) = 3/5(√5/5)+4/5(-2√5/5)

cos (A-B)  = 3√5/25 - 8√5/25

cos (A-B) = -5√5/25

cos (A-B) = -√5/5

Hence the value of cos (A-B) is -√5/5

relating to or denoting a system of numbers and arithmetic based on the number ten, tenth parts, and powers of ten.

it alot will look like this 4.4

step-by-step explanation:

if you want to solve percent error follow these steps.

1. subtract the accepted value from the experimental value.

2. take the absolute value of step 1.

3. divide that answer by the accepted value.

4. multiply that answer by 100 and add the % symbol to express the answer as a percentage.

if you want to solve percent of change just do this.

1. work out the difference (increase) between the two numbers you are comparing.

2. divide the increase by the original number and multiply the answer by 100. if your answer is a negative number then this is a percentage decrease.

hope this : )