Math Training Center – Japanese University Entrance Exam 2009 (Trigonometric Identities) August 21, 2019 10 By Stanley Isaacs Related posts: No related posts.

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