Question

11

求解紅筆部分！謝謝！

C. 試求√3(csc 20°+sec10°)−(sec20°+csc10°)的值=
(13
sin sin = 646
(1320² + 3710²)
) - ( 1032
1/2 = seu
coś wy
ZM40°= 2572d0s20°
2
=
sin 20⁰
t
√3
cos 100
Blosz0°-sinzoº
sin 20° coszo
1.500
2 sin 40
= sin 40°
+
√35m10+ cos100
)
cos 10:sin 10°
2 sin (-20°)
— sin 20⁰
4+ (-4)= 0 +
#
1

Answer 1

✨ 最佳解答 ✨

qn

正餘弦疊合
√3cos20°-sin20°
=2[(√3/2)cos20°-(1/2)sin20°]
=2[sin60°cos20°-cos60°sin20°]
=2sin(60°-20°)=2sin40°

√3sin10°-cos10°
=2[(√3/2)sin10°-(1/2)cos10°]
=2[cos30°sin10°-sin30°cos10°]
=2sin(10°-30°)=2sin(-20°)