63.3k views
1 vote
40 POINTS !!!!!PLEASE HELPPP!!!!!!

40 POINTS !!!!!PLEASE HELPPP!!!!!!-example-1
User Wzs
by
6.6k points

2 Answers

7 votes

Answer:

cos(theta) = 3sqrt(58)/58

sin(theta) = 7sqrt(58)/58

Explanation:

Cos(2theta) = 2cos²(theta) - 1

-20/29 = 2cos²(theta) - 1

2cos²(theta) = 9/29

cos²(theta) = 9/58

cos(theta) = sqrt(9/58)

cos(theta) = 3sqrt(58)/58

sin²(theta) = 1 - cos²(theta)

sin²(theta) = 1 - 9/58

sin²(theta) = 49/58

sin(theta) = sqrt(49/58)

sin(theta) = 7sqrt(58)/58

sqrt: square root

User JuliusG
by
7.2k points
3 votes

Answer:

sin(a) =
(7√(5) )/(20)

Explanation:

cos(2a) = cos²(a)-sin²(a) = [1-sin²(a)]-sin²(a)= 1 - 2sin²(a)

1 - 2sin²(a) = -20/29

- 2sin²(a) = -49/40

sin²(a) = 49/80

sin(a) =
\sqrt{(49)/(80) }

sin(a) =
(√(49) √(80) )/(80) =
(7*4√(5) )/(80)

sin(a) =
(7√(5) )/(20)

User Bhumeshwer Katre
by
7.4k points