Write the cubic term for the Taylor series expansion of f(x) = sin(x) at c = pi/4

I did the work, can you please check for me whether my work is right?

Step-by-step explanation:

Close, the second term should have an exponent of 1.

f(x) = f(c) + f'(c) (x−c)¹/1! + f''(c) (x−c)²/2! + f'''(c) (x−c)/3!

f(x) = 1/√2 + 1/√2 (x−π/4) − 1/(2√2) (x−π/4)² − 1/(6√2) (x−π/4)³

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240