Help Please!
If tan θ = 20/21, what is cos θ?

We can use SOH CAH TOA.

We know that the legs, being Opposite and Adjacent, are 20 and 21. Using Pythagorean Theorem, we see the Hypotenuse is 29.

Then, using Adjacent over Hypotenuse, we know cos θ = 21/29.

option a is correct.

step-by-step explanation:

scale factor: it is used to find proportional measurements.

proportions means having the same ratio.

scale factor is the ratio of the model measurement to the actual measurement in a simplest form.

or we can say that the ratio of any two corresponding lengths in two similar geometric figures

if the scale factor is more than 1, then it is an enlargement,

if the scale factor less than 1, then it is a reduction.

given the two geometric figure:

by definition of proportions, we have