Math Training Center – Japanese University Entrance Exam 2009 (Trigonometric Identities) August 21, 2019 10 By Stanley Isaacs

you need to make an update of complicated japanese math really soon in 2013

english sub?????

Isn't he speaking in Korean??

yes is korean

Be the equation ax^2+bx+c=0, the roots are α and β . So : α+β = c/a ; α*β = -c/a

But in equation x^2-4x+1=0, the product between α*β = 1/1 = 1. So: α*β = 1 , β= 1/α

we know by data of problem : α = cos ϴ/(1+sinϴ), then β= (1+sinϴ)/cos ϴ

Now : α+β = -(-4)/1 = 4. So: α+β = 4.

Replace α and β datas of problem → α+β = cos ϴ/(1+sinϴ) + (1+sinϴ)/cos ϴ = 4

→ [cos² ϴ+ (1+sinϴ)²]/[ (1+sinϴ)cos ϴ] = 4 → [cos² ϴ + 1 + 2sinϴ + sin²ϴ]/[ (1+sinϴ)cos ϴ] = 4

→ [ 2+2sinϴ]/[ (1+sinϴ)cos ϴ] = 4 → 2(1+sinϴ)/[(1+sinϴ)cos ϴ] = 4 → 2/cosϴ = 4

→ 1/cosϴ = 2 → cosϴ= 1/2

As 0<ϴ<90º, finally ϴ = 60º

korean;;

It's korean

It's korean

hes really good at using the chalks too

I ain't no Japanese but I have been watching anime and movies for 7 years now and I can say he is not speaking Japanese it's Korean