<span>2.1e-10
= 2.1 x 10^-10
= 0.00000000021
hope it helps</span>
The third one is correcte
Answer:




Step-by-step explanation:
Given

Required
Solve (a) to (d)
Using tan formula, we have:

This gives:

Rewrite as:

Using a unit ratio;

Using Pythagoras theorem, we have:




Take square roots of both sides

So, we have:


Solving (a):

This is calculated as:


Where:


So:




Solving (b):

This is calculated as:

Where:
---- given
So:


Solving (c):

In trigonometry:

Hence:

Solving (d):

This is calculated as:


Where:


So:



You don't need to regroup when adding a two-digit number with a number.
Answer:
A = 119 units²
Step-by-step explanation:
side of square is (12√2)sin45 = 12
The portion of the diagonal that is NOT octagon is
12√2 - 12
There are four corner triangles. The sum of their areas is
(12√2 - 12)²
Area of the octagon is area of the square minus four corner triangle areas.
A = 12² - (12√2 - 12)²
A = 119.2935...