86

# TR Smith(calculus-geometry)

Joined 5 years ago from Eastern Europe. Last activity 3 days ago.

459

217

37

T. R. Smith writes tutorials and articles based on her teaching notes, math problems encountered at her day job, and things of personal interest to her.

Show: All
• All
• Education and Science (8)
• Games, Toys, and Hobbies (12)
• All
• Arts and Design (7)
• Autos (1)
• Books, Literature, and Writing (1)
• Education and Science (390)
• Entertainment and Media (2)
• Family and Parenting (1)
• Fashion and Beauty (1)
• Food and Cooking (2)
• Games, Toys, and Hobbies (25)
• Health (1)
• Home (4)
• Personal Finance (5)
• Pets and Animals (2)
• Religion and Philosophy (6)
• Sports and Recreation (4)
• Technology (6)
• 9

### Hexagon Shape Counting Puzzle: How many hexagons can you find in the diagram below?

3 years ago

A hexagon is any 2D shape with 6 sides.

• 7

### How many quadrilaterals do you see in the image below?

3 years ago

A quadrilateral is any 4-sided polygon. Use the symmetry of the diagram to help you count them all.

• 5

### How many triangles do you see in the image below?

3 years ago

Use the geometry symmetry of the puzzle to count them more efficiently!

• 3

### Geometry Genius Puzzle: How many quadrilaterals can you see in the figure below?

4 years ago

A quadrilateral is any polygon with 4 sides.

• 7

### Quadrilateral Counting Puzzle: How many quadrilaterals can you find in the figure below?

4 years ago

• 3

### A 1-by-1 grid square contains 1 rectangle, and a 2-by-2 grid square contains 9 rectangles.

3 years ago

Going up further in size, 3-by-3 grid square contains 36 rectangles, and a 4-by-4 grid square contains 100 rectangles. How many rectangles are contained in a 5-by-5 grid square? Can you discover the formula, in terms...

• 12

### How many triangles can you count in the diagram below?

3 years ago

Hint: the only kinds of triangles it contains are isosceles right triangles.

• 3

### Geometry Brain Teaser: Can you put two equilateral triangles together to form a pentagon?

4 years ago

No complicated dissection and reassembly required.

• 2

### Brain Teaser: 16 dots are arranged in 4 rows and 4 columns on a square grid.

4 years ago

What is the minimum number of straight lines needed to connect all the dots -- with the restriction that each new line must start at the end of the previous line, and no more than one new line can start at the end of a...

• 13

### How many rectangles can you find in the figure below?

3 years ago

• 7

### How many different triangles can you spot in the figure below?

4 years ago

Hint: Labeling the pieces may help you count the all triangles without missing any or counting any twice.

• 2

### Can you arrange the numbers 1 through 15 in the hexagonal cells shown below

3 years ago

so that the sum of the numbers along each side of the triangle is the same AND so that the product of the numbers at the vertices (pink cells) equals the product of the numbers in the middle (green cells) ? Hint: The...

• 3

### Three cylindrical barrels are stacked as shown in the figure below. The bottom two barrels

4 years ago

each have a radius of 20 cm. The top barrel has a radius of 9 cm. If they are all stacked on a flat floor, what is the total height of the stack? Hint: You don't need to apply the formula for the volume of a cylinder...

• 3

### Find three ways to write a mathematical expression that equals 100 using only the digits 1-9 and the

4 years ago

symbols +, -, /, x (times), ^ (exponent), (, ), and ! (factorial). You must use each of the nine digits exactly once, but the operations can be used as many or as few times as needed. Here's an example of...

• 2

### Can you label all the circles with the digits 0 through 9 so that

17 months ago

the sum of the four digits on each side of the triangle is the same for all three sides? (Each digit is used exactly once.) Can you figure out how to arrange the digits so that the side sums are equal and at a minimum...

• 5

### The smaller gray circles inscribed within the larger circle have equal sizes.

4 years ago

They are all tangent to one another as well as to the larger circle. If the smaller circles each have a radius of 20, what is the radius of the larger circle?

• 2

### Can a circle have both a rational circumference and a rational area?

4 years ago

If yes, what radius (or radii) will produce that result? If no, why not?

• 2

### If x and y are irrational numbers, and x/y and xy are both rational, is x+y rational as well?

4 years ago

If the answer is always yes, why? If sometimes yes and sometimes no can you provide example pairs of x and y to show that sometimes x + y is rational and sometimes it isn't. If the answer is always no, can you prove...

• 3

### Find two irrational numbers whose sum and product are rational numbers.

4 years ago

• 5

### What is 1 - 2 + 3 - 4 + 5 - ... + 99 - 100?

6 days ago

Can you find the value of the alternating addition/subtraction expression above without using a calculator? If so, how do you calculate it?

working