Answer:
Part 5.1.1:

Part 5.1.2:

Step-by-step explanation:
We are given that:

Part 5.1.1
Recall that:

Let θ = 2<em>A</em>. Hence:

Square the original equation:

Hence:

Subtract:

Take the square root of both sides:

Since 0° ≤ 2<em>A</em> ≤ 90°, cos(2<em>A</em>) must be positive. Hence:

Part 5.1.2
Recall that:

We can use the third form. Substitute:

Solve for cosine:

In conclusion:

(Note that since 0° ≤ 2<em>A</em> ≤ 90°, 0° ≤ <em>A</em> ≤ 45°. Hence, cos(<em>A</em>) must be positive.)
4x+28 +6x -15=-7x +64
10x+13=-7x +64
10x-7x=64-13
3x=51
x=17
I hope I helped you=)
20 is the answer to that!
:D
✽ - - - - - - - - - - - - - - - ~Hello There!~ - - - - - - - - - - - - - - - ✽






✽
➶ Hope This Helps You!
➶ Good Luck (:
➶ Have A Great Day ^-^
↬ May ♡