Question

can you help me on this problem?

Answer 1

Given sin theta=\[2\sqrt{10}/7\] and pie/2 is less than theta is less than pie. find cos(theta/2)

Answer 2

answer choices...

Answer 3

a ) \[-2\sqrt{14}/7\]
b) \[2\sqrt{14}/7\]
c) \[\sqrt{14}/7\]
d) none of the above

Answer 4

@acxbox22 think you can help?

Answer 5

@ganeshie8

Answer 6

sorry i am not good with trignometry :(

Answer 7

@zepdrix @iambatman

Answer 8

use half angle formulas, since \(x\) is in second quadrant, \(\frac{x}{2}\) will be in first quadrant and thus positive :
\[\cos(\frac{x}{2})=\sqrt{\dfrac{1+\cos(x)}{2}}\]

Answer 9

find the value of \(\cos(x)\) and plug it in above

Answer 10

how would I find that? :/

Answer 11

draw a triangle based on given info : \(\sin(x) = \dfrac{2\sqrt{10}}{7}\)