BBC2 个月
How to show a cone's surface area = π × r × slant length
Take the bottom part of the circle and roll it into a cone. Image caption, STEP 2: Unroll it and fold the shape in half vertically. Use a ruler to draw along the fold, then shade half of the shape ...
BBC7 年
How to prove a cone's surface area = π × r × slant length
Take the bottom part of the circle and roll it into a cone. Image caption, STEP 2: Unroll it and fold the shape in half vertically. Use a ruler to draw along the fold, then shade half of the shape ...