Enumerating All Domains in the techcorp.local

 Get-ForestDomain -Forest techcorp.local

Enumerating Trust for us.techcorp.local

Get-DomainTrust

Getting External Trust

Get-ForestTrust -Forest techcorp.local

Enumerating us.techcorp.local Trusts

Get-DomainTrust -Domain us.techcorp.local