Math Training Center – Japanese University Entrance Exam 2009 (Trigonometric Identities) August 21, 2019 10 By Stanley Isaacs Related posts: No related posts. CategoryArticles BlogTags11 24 3 10 Comments Taki Wok says: April 21, 2013 at 3:30 pm you need to make an update of complicated japanese math really soon in 2013 Reply billie 17 says: June 20, 2014 at 2:47 pm english sub????? Reply 나탈리아 says: October 26, 2015 at 11:54 am Isn't he speaking in Korean?? Reply Adriana Campos says: February 23, 2016 at 3:21 am yes is korean Reply Alfredo Telles Mosquera says: February 23, 2017 at 4:35 pm Be the equation ax^2+bx+c=0, the roots are α and β . So : α+β = c/a ; α*β = -c/aBut in equation x^2-4x+1=0, the product between α*β = 1/1 = 1. So: α*β = 1 , β= 1/αwe know by data of problem : α = cos ϴ/(1+sinϴ), then β= (1+sinϴ)/cos ϴNow : 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= 1/2As 0<ϴ<90º, finally ϴ = 60º Reply fx 570es says: November 6, 2017 at 7:45 pm korean;; Reply Edward Willim says: December 14, 2017 at 2:09 pm It's korean Reply Edward Willim says: December 14, 2017 at 2:09 pm It's korean Reply Nwan Tan says: May 6, 2018 at 8:19 am hes really good at using the chalks too Reply Trail Blazer says: April 2, 2019 at 3:40 pm 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now and I can say he is not speaking Japanese it's Korean Reply Leave a Reply Cancel reply Your email address will not be published. Required fields are marked *Comment Name * Email * Save my name, email, and website in this browser for the next time I comment.