Answer: sin = ±
Step-by-step explanation:
We very well know that,
cos2A=1−2sin²A
⟹ sinA = ±
As required, set A = & cos a=
,thus we get
sin =±
∴ sin =±
= ±
since ,360° < <450°
,180° < <225°
Now, we are to select the value with the correct sign. It's is obvious from the above constraints that the angle a/2 lies in the III-quadrant where 'sine' has negative value, thus the required value is negative.
hope it helped!
Answer:
A. T > 2.539
Step-by-step explanation:
We have a hypothesis test of the mean, with unknown population standard deviation.
The hypothesis are:
From the hypothesis we can see that the test is right-tailed, so the critical value of t should be a positive value.
The degrees of freedom can be calculated as:
The significance level is 0.01, so the critical value tc should be the one that satisfies:
Looking up in a t-table, for 19 degrees of freedom, this critical value is tc=2.539.
