Angle of the sector

Find the angle of the sector of a circle radius of 20 units where the area is equal to the lateral area of a cone with a radius of 8 units.

Correct answer:

α =  81.4587 °

Step-by-step explanation:

r1=20 r2=8  h2=r2=8 s=h22+r22=82+82=8 211.3137 A=π r2 s=3.1416 8 11.3137284.3445  A = π r12   α/360  α=π r12360 A=3.1416 202360 284.3445=81.4587=81°2731"



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