P = πr + 2r + 2a
P = 84
r = 6.7
Work out the value of a.
Give your answer correct to 3 significant figures.
+426 Perimeter = π * 6.7 + 2 * 6.7 + 2a
= 6.7π + 13.4 + 2a
Perimeter = 84
Since both are equal,
6.7π + 13.4 + 2a = 84 | -13.4
6.7π + 2a = 70.6 calculate π using my calculator
Calculator Screen (Diagram 1)
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6.7π
21.04867078
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21.04867078 + 2a=70.6 | -21.04867078
Calculator Screen (Diagram 2)
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70.6 - Ans
49.55132922
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2a = 49.55132922 | ÷2
Calculator Screen (Diagram 3)
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Ans ÷ 2
24.77566461
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a = 24.77566461
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Using Sci 3 (three significant figures + scientific notation),
Calculator Screen (Diagram 4)
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Ans ÷ 2
2.48×101
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Pressing ENG (engineering),
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Ans ÷ 2
24.8×100
a ≈ 24.8 (3 significant figures)
Calculator Details
CASIO fx-96SG PLUS
