Question

If a=13 , b =12 , c =5 , then cos( A /2) =​

Answer 1

Step-by-step explanation:

ok but i can't understand

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Answer 2

Answer:

We have,

a=13

b=12

c=5

Then, we know that

cosA=

2bc

b

2

+c

2

−a

2

cosA=

2×12×5

12

2

+5

2

−13

2

cosA=

120

144+25−169

cosA=

120

169−169

cosA=

120

0

cosA=0

cosA=cos

2

π

A=

2

π