Problem 1 (sin20 + 2sin40) / cos20 hope

Problem 1 (sin20 + 2sin40) / cos20 hope

sin20+2sin40)/cos20
=[(sin20+sin40)+sin40}/cos20
=[2sin30cos10+sin40}/cos20
=[sin80+sin40)+sin40}/cos20
=[sin(60+20)+sin(60-20)}/cos20
=[sin60cos20+sin20cos60+sin60cos20-sin20cos60]/cos20
=2sin60cos20/cos20
So simple, are you a junior high school student?
The uncles upstairs are old. They haven't learned math well since they were 70

2 cos 10 / cos 20 simplification

tan20／2sin10

What is sin 22 ° 30 'equal to?

Let a = 22 degrees and 30 minutes
Then cos45 = cos2a = √ 2 / 2
cos2a=1-2sin²a=√2/2
sin²a=(2-√2)/4
Obviously, Sina > 0
So the original formula = [√ (2 - √ 2)] / 2