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In a DeltaABC, if a = 4, b = 5 , c = 6 t...

In a `DeltaABC`, if a = 4, b = 5 , c = 6 then angle C is equal to

A

A

B

`1/2A`

C

2A

D

3A

Text Solution

Verified by Experts

We have,a=4 b=5 and c=6
`thereforecosA=(b^(2)+c^(2)-a^(2))/(2bc)` and, `cosC=(a^(2)+b^(2)-c^(2))/(2ab)`
`rArrcosA=3/4` and `cosC=1/8`
`rArrcosC=2cos^(2)A-1rArrcosC=cos2ArArrC=2A`
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