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Question Number 20847 by j.masanja06@gmail.com last updated on 04/Sep/17

t h e r e c t a n g l e i s k n o w n t o b e t w i c e

a s l o n g a s i t s w i d e . i f t h e w i d t h i s

m e a s u r e d a s 20 \pm 0.2 c m .

f i n d t h e a r e a i n t h e f o r m o f (A \pm b)

Answered by ajfour last updated on 04/Sep/17

A = l w a n d a s l = 2 w

A = 2 w^{2} = 2 \times {(20)}^{2} = 800 {c m}^{2}

\Rightarrow Δ A = 4 w Δ w = 4 \times 20 (\pm 0.2) {c m}^{2}

= \pm 16 {c m}^{2}

A r e a = A + Δ A = 800 {c m}^{2} \pm 16 {c m}^{2} .

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