Question

In `DeltaABC, BC=CA` and `angleA=40^(@)`. Find the largest side of `DeltaABD`.

Answer 1

In `DeltaABC`
`AC=BC`
`implies" "angleABC=angleBAC`
`implies" "angleABC=40^(@)`
Now, `angleA+angleB+angleC=180^(@)`
`implies" "40^(@)+40^(@)+angleC=180^(@)`
`implies" "angleC=180^(@)-80^(@)=100^(@)`
Now, `angleC` is the greatest angle in `DeltaABC`.
`:.` Its opposite side AB will be the largest side.