Question

〈sin65°+sin15°×sin10°〉/〈sin25°—cos15°×cos80°〉的值

Answer 1

原式＝[sin(90°-25°)+sin15°sin10°]/[sin(15°+10°)-cos15°cos(90°-10°)] ＝(cos25°+sin15°sin10°)/(sin15°cos10°＋cos15°sin10°-cos15°sin10°) ＝[cos(15°+10°)+sin15°sin10°]/sin15°cos10 ...