Question

In triangle ABC , if BC = 3, CA=4, AB= 5 cos angle BAC is _______________,​

Answer 1

❄️ ANSWER ❄️

• AE 2= 973

❄️ SOLUTION ❄️

BD=DE=EC=

35 and △ABC is a right angled triangle.

Now

cosC= .AC.EC

AC 2+EC 2−AE 2

Or

AE 2=AC 2 +EC 2 −2.AC.EC.cosC

Or

=4 2+( 35) 2 −2.8. 35.cosC

=16+ 925 − 3

2×4×5. 54

Or

= 9169− 332

= 9169−96

= 973 .

Hence

AE

2= 973

AE.4

AE

2+4

2 − 35

•(AE 2= 973)•