The height of a cone is 12cm, and it is semicircle when the side is unfolded? Urgent···· Before 8 o'clock

The height of a cone is 12cm, and it is semicircle when the side is unfolded?
Side area: 12 * 12 * 3.14/2 = 226.08 square centimeter
Total area: 12 * 2 * 3.14/2 = 37.68cm
37.68/3.14/2 = 6cm
6 * 6 * 3.14 = 113.04 square centimeter
226.08 + 113.04 = 339.12 square centimeter

The height of a cone is 12cm, and the side view is semicircle
Such as the title

Since the side view is a semicircle, the circumference of the bottom of the cone is equal to the circumference of the semicircle, so the radius of the bottom is half of the radius of the semicircle

With a piece of 20 cm long and 12 cm wide cardboard to form a column, standing on the table, its height may be () cm or () cm
The energy is () cm and the side area is () square cm

The height is 12 or 20 and the side area is 240

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The height of a cone is 12cm, and it is semicircle when the side is unfolded? Urgent···· Before 8 o'clock