设直角边是a和b斜边4-a-ba²+b²=(4-a-b)²=16+a²+b²-8a-8b+2abab-4a-4b+8=0a+b=(ab+8)/4>=2√(ab)令x=√(ab)x²+8>=8xx²-8x+8>=0x=4+2√2因为a+b