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แบบฝกหัดที่ 7

1. ถังเก็บน้ํามันของปมแหงหนึ่งเปนรูปทรงกลม มีเสนผานศูนยกลาง 7 เมตร ตองการทาสีครึ่ง
ทรงกลมบน โดยเสียคาทาสีตารางเมตรละ 40 บาท ตองเสียคาทาสีกี่บาท

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ี
2. หินออนทรงลูกบาศกมขนาดดานละ 2.1 เมตร ถาตองการกลึงใหเปนรูปทรงกลมใหมขนาดเสนผาน
ี
ศูนยกลางเทากับความยาวของดานลูกบาศก จงหาวาจะตองกลึงหินออกไปปริมาตรเทาใด
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3. นําแทงตะกั่วทรงสี่เหลี่ยมมุมฉากกวาง 8 นิ้ว ยาว 11 นิ้ว หนา 5 นิ้ว ไปหลอมเปนลูกปนทรงกลมขนาด
รัศมี 1 นิ้ว จะหลอมไดกี่ลูก

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