Cos law

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MB=BD= x

8+x = 9+(7-x)

8+x =16-x

2x = 8

x =4

Cos law

49 = 64+81-144Cos A

Cos A = 49-64-81/-144=96/144

A=48

A/2 =24

r/12=tan 24

r= 5.4

 

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