Question

Can someone please help with this it’s urgent!!

Answer 1

Answer:

a) 3 cm

b) 140 cm²

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Equality Properties

Geometry

• Circumference: C = 2πr
• Surface Area of a Cylinder:  SA = 4πr²

Step-by-step explanation:

Step 1: Define

C = 21 cm

Step 2: Find Radius r

1. Substitute [C]:                    21 = 2πr
2. Isolate r:                             21/(2π) = r
3. Rewrite:                              r = 21/(2π)
4. Evaluate:                            r = 3.34225 cm
5. Round:                                r ≈ 3 cm

Step 3: Find Surface Area

1. Substitute [SAS]:                     SA = 4π(3.34225 cm)²
2. Exponents:                              SA = 4π(11.1707 cm²)
3. Multiply:                                   SA = 44.6826π cm²
4. Multiply:                                   SA = 140.375 cm²
5. Round:                                     SA ≈ 140 cm²