题目如图,PAPAPA与⊙O\odot O⊙O相切于点AAA,POPOPO交⊙O\odot O⊙O于点BBB,点CCC在PAPAPA上,且CB=CACB=CACB=CA.若OA=5OA=5OA=5,PA=12PA=12PA=12,则CACACA的长为______.知识点:切线长定理章节:图形的性质 / 圆