A, B and D are true
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2.1 2.19 2.2 2.3 2.54 2.6

We will use trigonometric identities to solve this. I will use θ (theta) for the angle.
First of all, we know that cotθ = 1/tanθ. This is a trigonometric identity.
We can replace cotθ in the expression with 1/tanθ.

Simplify: 1/tanθ * tanθ = tanθ/tanθ = 1
So now, we have:

Next, we also know that secθ = 1/cosθ. This is another trigonometric identity.
We can replace secθ with 1/cosθ in our expression.

Simplify:

Our third trigonometric identity that we will use is tanθ = sinθ/cosθ.
We can replace sinθ/cosθ with tanθ.
Now we have as our final answer:

Hope this helps!
Answer:
a = 6.7m is the answer.
Step-by-step explanation:
a = ?
b = 6m
c = 9m
According to the Pythagorean theorem,
a² + b² = c²
a² + 6² = 9²
a² + 36 = 81
a² = 81 - 36
a² = 45
a = 6.708
round to the nearest tenth,
a = 6.7m
∴ Janice is 6.7m high up in the air.
Answer:
R=30.81≈31
Step-by-step explanation: