計(jì)算:
①96°-18°26′59′
②83°46′+52°39′16″
③20°30′×8
④105°24′15″÷3
解:①96°-18°26′59′=77°33′1″;
②83°46′+52°39′16″=136°25′16″;
③20°30′×8=164°;
④105°24′15″÷3=35°8′5″.
分析:①兩個(gè)度數(shù)相減,被減數(shù)可借1°轉(zhuǎn)化為60′,借一分轉(zhuǎn)化為60″,再計(jì)算;
②兩個(gè)度數(shù)相加,度與度,分與分,秒與秒對(duì)應(yīng)相加,分的結(jié)果若滿60,則轉(zhuǎn)化為度;
③度數(shù)乘以一個(gè)數(shù),則用度、分、秒分別乘以這個(gè)數(shù),秒的結(jié)果滿60則轉(zhuǎn)化為分,分的結(jié)果滿60則轉(zhuǎn)化為度.
④度數(shù)除以一個(gè)數(shù),則用度、分、秒分別除以這個(gè)數(shù),秒不夠則從分中轉(zhuǎn)化,分不夠則從度中轉(zhuǎn)化.
點(diǎn)評(píng):此類題考查了度、分、秒的減法、加法、乘法、除法計(jì)算,相對(duì)比較簡(jiǎn)單,注意以60為進(jìn)制即可.