Math mini-contest problem for Day 27 on D.Buzz for February 2021 😎

Math mini-contest problem for Day 27 on D.Buzz 😎

Fang, Vision, and Manga are solving for missing values of the triangle ABC. Fang was able to get sin (A) = 4/5, while Vision got sin (2A) = 19/20. Manga needs to solve for cos (A). What is the exact value of cos (A)?

H2
H3
H4
3 columns
2 columns
1 column
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