Pangos shot 8 of 13 from the field, including 5 of 8 on 3-pointers, as Gonzaga (4-0) scored at least 90 for the third time this season.
Freshman guard Ike Iroegbu had 20 points to lead cold-shooting Washington State (2-1). DaVonte Lacy added 14.
Washington State was held to 44 percent shooting by Gonzaga, which shot 55 percent. The Bulldogs had 20 assists and outrebounded the Cougars 35-30.
Gonzaga scored the first basket of the game and never trailed. The Bulldogs made six of their first eight shots to take a 16-6 lead, capping the run on a 3-pointer by Barham.
Jordan Railey's basket brought WSU to 24-18, but Barham's third 3-pointer extended the lead to 29-20.
Sam Dower Jr. completed a three-point play and Gary Bell Jr. sank a long 3 as Gonzaga pushed its advantage to 37-25. Pangos' 3-pointer a minute later made it 40-26.
Washington State put together a 7-2 run that started when Iroegbu was fouled and sank all three free throws. The Cougars pulled to 43-33 with 3:39 left in the first, but Pangos answered with a pair of 3s and Washington State was scoreless the rest of the half, allowing the Zags to go into halftime ahead 49-33.
Washington State shot just 35 percent in the first half, including 3 of 13 from 3-point range. Gonzaga was at 55 percent, including 8 of 14 on 3-pointers. Pangos scored 20 points in the opening 20 minutes, while Iroegbu had 15.
Przemek Karnowski opened the second half by completing a three-point play for Gonzaga to push the lead to 52-33.
But the Cougars were not done. Lacy, Dexter Kernich-Drew and D.J. Shelton all sank 3-pointers to bring WSU within 54-42 early in the second. A layup by Royce Woolridge cut Gonzaga's lead to 57-48 with 15 minutes left.
Gonzaga replied with a 13-4 run, including a pair of 3s by Barham, to rebuild the lead to 70-52.
Unanswered baskets by Barham, Kyle Dranginis and David Stockton pushed Gonzaga's advantage to 77-54 with 10:08 left, and the Cougars did not threaten again.
Gonzaga edged Washington State 71-69 last season, but the Cougars lead the series 98-50.
Gonzaga is 124-8 in the McCarthey Athletic Center since it opened in 2004.