Please help me Tramserran mam...

 see proof below

Step-by-step explanation:

Use the following when solving the proof...

Double Angle Identity: cos2A = 1 - 2sin²B

Pythagorean Identity: cos²A + sin²A = 1

note that A can be replaced with B

Proof from LHS → RHS

Given:                            cos²A + sin²A · cos2B

Double Angle Identity: cos²A + sin²A(1 - 2sin²B)

Distribute:                      cos²A + sin²A - 2sin²A·sin²B

Pythagorean Identity:                        1 - 2sin²A·sin²B

Pythagorean Identity:   cos²B + sin²B - 2sin²A·sin²B

Factor:                           cos²A + sin²B(1 - 2sin²A)

Double Angle Identity: cos²B + sin²B · cos2A

cos²B + sin²B · cos2A = cos²B + sin²B · cos2A  

x=half

step-by-step explanation:

b: |12 – x| ≤ 0.25

step-by-step explanation:      

let x be the possible lengths in inches, of the ribbons jaime cut.

we have been given that jaime is cutting strips of ribbon for a project. he tries to cut each piece to be 12 inches long, but sometimes he cuts it too long or too short by as much as 0.25 inch.  

we can represent this information in an inequality as:

by the definition of absolute value function we will get,

upon combining our inequalities we will get,

therefore, the inequality   describes all the possible lengths (x), in inches, of the ribbons jaime cut.

step-by-step explanation: