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In a Delta ABC if angle A=90^@, then cos...

In a `Delta ABC` if `angle A=90^@`, then `cos^(-1)(( R)/(r_2 +r_3))` is equal

A

` 90 ^(@) `

B

` 30 ^(@) `

C

` 60 ^(@) `

D

` 45 ^(@) `

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The correct Answer is:
C
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