Question

cos15度减sin15度除以cos15度加sin15度的值

Answer 1

[cos(15°)-sin(15°)]/[cos(15°)+sin(15°)]

=[cos(15°)-sin(15°)]²/[cos(15°)-sin(15°)][cos(15°)+sin(15°)]

=[cos²(15°)+sin²(15°)-2sin(15°)cos(15°)]/[cos²(15°)-sin²(15°)]

=[1-sin(30°)]/cos(30°)

=(1/2)/(√3/2)

=√3/3