**SDG**

Sustainable Development Goal 6 is about "clean water and sanitation for all".

 In Estonia 60% - 80% of the trash that gets thrown into the water is plastic.

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**Task definition**

Find out the area of the triangle (the smaller one) measure it from the corners. You can calculate the area two ways. Then use a part of the number that you got to find out what is the maximum reading of most Japanese cars speedometers. For the last part subtract 100 from the previous number that you got to find out the last answers.  Last answer difference is 20.

**Solution move**

1.  Measure the triangle from corners
2.  Use a part of the number
3.  Substract 100 from the previous number
4.  Last answer differences is 20.

**Mathematical calculation step**  
Solution 1.

 (alus x kõrgus)S= a×h:2=  
574×627,48:2= 180 086 cm²  
Solution 2.  
p= a+b+c  
690+690+574:2 = 977  
S=√ p (p-a)(p-b)(p-c)=  
S=√977×(977-690)(977-690)(977-574)=  
S=√977×287×787×403= √324 312 287 39=  
180 086 cm²  
Use A part of the number 180 086= 180km/h  
for the last part subtract 100 from the previous number  
180-100= 80

Hint 1

Solution 1.   
S= a×h:2=

Hint 2

p= a+b+c  
S=√ p (p-a)(p-b)(p-c)=

The area of the triangle is 180 086 cm²

**Connection to the study**

 My study field Traffic safety is related to the part where you have to find out the maximum reading of Japanese cars speedometers is 180km/h.