In the triangle ABC, if angle B equals angle c equals 15 degrees and CD is perpendicular to the extension line of AB intersection Ba and point D, then angle ACD equals ()
∵∠CAD=∠ACB+∠B=15+15=30
∴∠ACD=90-∠CAD=60
∵∠CAD=∠ACB+∠B=15+15=30
∴∠ACD=90-∠CAD=60