my car has a leak on 2000 Ford Explorer

last week my car temperature went up a little more than normal(3/4) on the gauge. After about one minute it returned to normal. Today I changed the thermostat, but when we put water in the radiator we saw a leak . We could not see if it came from the radiator or the bottom hose. Is there any way for us to know where it comes from ?

Asked by for the 2000 Ford Explorer
Yes, get in there with a flashlight and mirror and trace the leak to the source.