🔍 Key Concepts

• Gear tooth profile is the shape of the side of the tooth, from root to tip, not just a distance or circle • In the illustration, some letters mark lengths or radii (like diameters or pitches), while others follow along a curved surface • Focus on which label is drawn along the full side of a tooth rather than between two specific points

💭 Think About

• Look at each labeled item F, H, I, and J and ask: is this marking a curve/shape or a straight measurement like height or thickness? • Which label appears to trace the working surface where two gear teeth actually slide or roll against each other? • Does the label you choose follow the contour of the tooth flank from near the root toward the tip, instead of just across the top or across the space?

✅ Before You Answer

• Verify that your choice shows a continuous contour instead of a single arrow straight across a gap or diameter • Check that the label is applied to one side of one tooth, not an entire circle or across multiple teeth • Confirm your choice matches the usual idea of a tooth flank shape (profile), not pitch, clearance, addendum, or dedendum