🔍 Key Concepts

• Thread angle shown in the sketch (note the 60° marking) • Difference in shape between V-shaped, trapezoidal (square-ish), and one-sided (buttress) thread forms • Which common thread forms use a 60° included angle versus 55° or other angles

💭 Think About

• Look closely at the outline of each thread tooth: are both sides the same angle, or is one side more vertical than the other? • Do the crests and roots look sharp, flat, or rounded in the sketch, and which named thread forms match that profile? • Which of the listed thread types is known for a 60° included angle, and which one is known for 55° or for a flat-topped trapezoid shape?

✅ Before You Answer

• Verify the included angle in the picture and match it to the standard angle for each option (e.g., 60° vs 55° vs others). • Check whether the thread crests and roots are pointed or flat in the illustration. • Eliminate any choices whose typical profile is not symmetric V-shaped with the given angle.