度分秒属于60进制.
(1) 原式=(56°+16°)+(23'+35')+(48"+43")
=72°+58'+(1'31")
=72°59'31"
(2) 原式=89°59’60”-28°12'36"
=61°47'24"
(3) 原式=(12°×4)+(34'×4)=48°+(136')
=48°+(2°16‘）
=50°16'
(4) 原式=(40°/6)+(40'/6)
=(6又2/3)°+(6又2/3)'
=(6°40‘)+(6'40")
=6°46′40“
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诚挚为你解答——来自广东广雅中学知识团队