Answer:
5.43×10^14 or

Step-by-step explanation:
Scientific notation, the number must always be less than 10, in this case 5.43. The exponent represents how much times I moved the decimal point to the left.
Hshhshs ssu sid si sisis s sis s s s is is sis si sis s s isis s i si
1. 4 • (–3) • 5
so 4 x (-3) = -12 and then -12 x 5 = -60
2. (2.25 x 23) x 4
so (2.25 x 23) 51.75 and then 51.75 x4 = 207
4. 5 x 12 x (-2)
so 5 x 12 = 60 and then 60 x (-2) = -120
5. 35(26)(0) =
so 35 x 26 = 910 and then 910 x 0 = 0
Pretty sure when you multiply something by 0 it is 0 <span />
Recall the angle sum identities:


Now,

Divide through numerator and denominator by
to get

Next, we use the fact that
lie in the first quadrant to determine that


So we then have


Finally,
