Blue Ring Area

 Find the blue area.

 

 

 

 

 

 

 

 

 

Source:@dment37 

Answer 25 pi square cm

Circle in the triangle

 

Resource: New Scientist

 

Triangle Rule Challenge

 

   source: @aap03102 and @MrJohnRowe

Problem 147: Sine and Cosine Rules Practice

resource: Don Steward

Rich Tasks 77: Triangles that have their perimeters and areas equal

further info here

Problem 137: Triangles of Sri Yantra

By Ranjithsiji - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=14796037

This is a photo of Shri Yantra, a diagram used in Hinduism. IT has a lot of triangles. How many triangles can you count? You can find a vector version below:

Problem 129: Congruent rectangles

Three Congruent Triangles. What is the angle?

source: Catriona Shearer

Problem 122: Square Root Graph Puzzle

Find the values of a, b, c and d. (All triangles are equilateral)

Resource: Diego Rattagi

Problem 119: Hypotenuse

Problem 101: Circle in the Triangle

Source: @ariya_7213

Problem 93: Triangle or Square?

Problem 89: 90-60-30

【オリジナル問題】６
図のように、3つの角が30°・60°・90°の直角三角形を6個つなげたとき、AB：BC＝[ ]である。 pic.twitter.com/c7u2jBP0kT

— den@オリジナル問題集⊿ (@sansu_original) February 9, 2019

View image on Twitter AB/BC ?

Problem 73: How many triangles?

How many triangles can you count?

Problem 70: Identical Triangles

Source: Jose Luis de Vila

Problem 61: Triangle and Circles

Problem 54: Isosceles Triangles

This is an isosceles triangle. Two of its sides are equal in length to each other.

How many such triangles exist given that their perimeter is 100 and all side lengths are whole numbers?

1. 24
2. 25
3. 49
4. 50
5. none

Problem 14: Triangles

Problem 13: Circles inside the square

The pink circle has radius R, and orange circle has radius r.

Find the length of R in terms of r.

This problem is moderated from here.

Beautiful Gifs 3: Pythagorean Theorem