M MEBC01 New member Joined Apr 1, 2020 Messages 8 Apr 1, 2020 #1 Find cos2β , given that sinβ = −4/5 and 3π/2 <β< 2π a. - 9/25 b. - 7/25 c. 7/25 d. 9/25 e. None of a – d. I do not even know where to start with this problem.
Find cos2β , given that sinβ = −4/5 and 3π/2 <β< 2π a. - 9/25 b. - 7/25 c. 7/25 d. 9/25 e. None of a – d. I do not even know where to start with this problem.
D Deleted member 4993 Guest Apr 1, 2020 #2 MEBC01 said: Find cos2β , given that sinβ = −4/5 and 3π/2 <β< 2π a. - 9/25 b. - 7/25 c. 7/25 d. 9/25 e. None of a – d. I do not even know where to start with this problem. Click to expand... Do you know that: cos(2β) = 1 - 2*sin2(β) Show us what can you do with that information.
MEBC01 said: Find cos2β , given that sinβ = −4/5 and 3π/2 <β< 2π a. - 9/25 b. - 7/25 c. 7/25 d. 9/25 e. None of a – d. I do not even know where to start with this problem. Click to expand... Do you know that: cos(2β) = 1 - 2*sin2(β) Show us what can you do with that information.
M MEBC01 New member Joined Apr 1, 2020 Messages 8 Apr 1, 2020 #3 Subhotosh Khan said: Do you know that: cos(2β) = 1 - 2*sin2(β) Show us what can you do with that information. Click to expand... I put it into the equation and got my answer. It was -7/25 Thanks.
Subhotosh Khan said: Do you know that: cos(2β) = 1 - 2*sin2(β) Show us what can you do with that information. Click to expand... I put it into the equation and got my answer. It was -7/25 Thanks.
