2 GCSE maths questions

Hi guys,

I've come across two GCSE maths questions which I really need help on. So if any of you guys can solve them, please help.

1. Emma is making party hats out of thin card. She starts with a circle of radius 10 cm and removes a sector AOB of angle 72 degrees and thros it away. Using the major sector, she joins OA and OB (without overlap) to make a cone. Find the volume of the cone in terms of pi.
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