Câu 72 Trang 96
Lớp 9 SGK Toán tập 2

Câu 72 Trang 96

Lời giải

Chu vi bánh xe là 540 mm => bán kính bánh xe là: $R=\frac{C}{2.\pi }=\frac{270}{\pi }(mm)$

Số đo cung có độ dài 200mm là: $n=\frac{180.l}{\pi .R}=\frac{200.180}{\pi .\frac{270}{\pi }}=\frac{400}{3}\approx 133^{\circ}$

Vậy: $\widehat{AOB}=133^{\circ}$

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