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In the figure, find AR

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#### Solution

∆AFI, ∆FRI are right triangles.

By Pythagoras theorem,

AF^{2} = AI^{2} – FI^{2}

= 25^{2} – 15^{2}

= 625 – 225

= 400

= 20^{2}

∴ AF = 20 feet.

FR^{2} = RI^{2} – FI^{2}

= 17^{2} – 15^{2}

= 289 – 225

= 64

= 8^{2}

FR = 8 feet.

∴ AR = AF + FR

= 20 + 8

= 28 feet.

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