Question

Given: cosθ= 4/5 Find: sin2θ

Answer 1

Answer:

cos theta=4/5

b/h=4/5

b=4 and h=5

p=?

H^2=P^2+B^2

5^2=P^2+4^2

25-16=P^2

9=P^2

$\sqrt{9}$=P

3=P

Now,

sin2theta

=p/h2

=3/5*2

=9/5

Step-by-step explanation:

Answer 2

Answer:

About 36.87 degrees; sinθ=3/5

Step-by-step explanation:

Note: I made an assumption with the Find: sin2θ part of your question, as it turned up as invalid when working on it on my end. Therefore, I assumed that it was sinθ. If it was something else, tell me and I can correct the answer/content.

Since within a triangle there are three sides when solving an angle, being opposite, adjacent and hypotenuse.

By already having cosθ=4/5. the rest of the problem can be solved. Since cosine is adjacent over hypotenuse, we can use the Pythagorean Theorem, solving for one of the legs of the triangle with:

c^2-b^2=a^2

Now, just plug in c as the 5 (the hypotenuse) and b as 4 (one of the legs).

5^2-4^2=a^2

25-16=a^2

9=a^2

a=3

The other leg is 3. With this, 3 would be the opposite angle from sin 20. Therefore, it can be plugged in the sine equation to get the answer. Remember, sine is Opposite/Hypotenuse.

sinθ=3/5

Move over the sine to then opposite side, inverse it:

θ=sin-1 3/5

Use a calculator.

θ = about 36.87 degrees.