This document provides steps for creating a formula in Excel to calculate missing angles in triangles and rectangles. It instructs the user to: 1) Set up labeled cells to enter known angles for a triangle or rectangle. 2) For a triangle, use the formula =180-(B3+B4) in cell B5 to calculate the missing angle based on the fact that interior angles of a triangle sum to 180 degrees. 3) For a rectangle, decide on a formula to calculate the missing angle based on the fact that interior angles of a rectangle sum to 360 degrees. 4) Save the Excel sheet as "Missing_Angle_Calculator" and test it by calculating missing angles for sample triangles

1. Creating Formulas in
Excel
Finding the missing angle of a triangle or rectangle

2. Step 1
Open up Excel

3. Step 2
In cell A1, type the word “triangles”
You may
change
color, font, size
when you are done
with the whole
assignment, not now.

4. Step 3
Skip a cell, in cell A3, type “
angle 1”
In cell A4, type “
angle 2”
In cell A5, type “
angle 3”

5. Step 4
We know that a triangle has a total of
180 degrees.
Do not type anything in B3 or B4 yet.
In B5, type the formula (exactly):
=180-(B3+B4) then press enter
(think about what this formula means,
you many need to explain it later)

6. Step 5
Let’s say we have a triangle, 1 side of
the triangle is 40 degrees, another is 30
degrees.
In B3 type 40, and in B4 type 30.
Don’t change anything in B5.
What comes up in B5? Is this correct?

7. Step 6
Repeat the process for the rectangles,
starting with writing “Rectangles” in
D1.
This time you will have 4 angles.
Decide what formula you will use. (raise
your hand if you don’t understand)

8. Step 7
Save your excel sheet in math folder as:
Missing_Angle_Calculator

9. Step 8
Answer the following questions (using
your excel creation)
Find the missing angle:
1. Triangle: side 1= 20°, side 2=70°, side 3=?
2. Triangle: side 1=30°, side 2=60°, side 3=?
3. Triangle: side 1= 73°, side 2= 15°, side 3=?
Write your
answers
down.

10. Step 8
Answer the following questions (using
your excel creation)
Find the missing angle:
4. Rectangle: side 1= 20°, side 2=70°, side
3=55°, side 4=?
Write your
5. Rectangle: side 1=39°, side 2=58°, side answers
down.
3=100°, side 4=?
6. Rectangle: side 1= 73°, side 2= 99°, side
3=111°, side 4=?

11. Step 9
You may customize your excel sheet
(change font, color, size, etc)