11.1 Study FIGURE 11.1 below and calculate the true length of AC - NSC Mechanical Technology Welding and Metalwork - Question 11 - 2021 - Paper 1

To find the true length of AC, we first calculate the length of BC:

1. Calculate the difference in diameters:

   $BC = \frac{90 - 50}{2} = 20$ mm

2. Apply the Pythagorean theorem:

   $AC^2 = AB^2 + BC^2$

   With AB as the radius of the upper circle (25 mm) and BC calculated:

   $AC^2 = 50^2 + 20^2$

   Calculating that gives:

   $AC^2 = 2500 + 400 = 2900$

3. Thus,

   $AC = \sqrt{2900} \approx 53.85$ mm, which rounds to 54 mm.