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# plz help

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https://vle.mathswatch.co.uk/images/questions/question17870.png

https://vle.mathswatch.co.uk/images/questions/question18040.png

Apr 22, 2020

#1
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First one,

"The perimeter of the triangle is 30"

Perimeter is the sum of outer lines of a shape.

(The three sides of this triangle)

so, 3a=30 thus a=10 cm

Rectangle's perimeter = 2(l+w)=2l+2w , given l=a and w=b then

2a+2b=30

Since a=10

20+2b=30 , 2b=10 , b=5

Area of square is side squared.

b is the side so $$b^2=5^2=25$$ $$cm^2$$

Apr 22, 2020
#2
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Second one,

Draw a line from B to D

Notice it is two right-angled triangles.

area of triangle $$\frac{1}{2}*b*h$$ (b=base, h=height)

so

Area of the first triangle: $$\frac{1}{2}*18*7.5=67.5cm^2$$

Area of the second triangle: $$\frac{1}{2}*15.6*11.7=91.26cm^2$$

Thus area of the quadrilateral is the sum of both

$$67.5+91.26=158.76cm^2$$

Apr 22, 2020