In this paper, we prove an isoperimetric inequality for the triangular grid graph which was conjectured by Adams, Gibson, and Pfaffinger, using the compression technique of Bollobás and Leader. Moreover, we apply the isoperimetric inequality to the Zero-Visibility Search game and Lions and Contamination game in order to obtain lower bounds for the inspection number and lion number respectively. We also provide searching strategies to prove upper bounds for both the inspection number and lion number.