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3 years ago

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An equilateral triangle with side length 7 cm is shown in the diagram, work out the area of the triangle.

1 answer:

ElenaW [278]3 years ago

8 0

If a triangle has sides of 7 cm and it is an equilateral you can draw a line right down the middle to form two congruent triangles.

These smaller triangles have a hypotenuse of 7cm and a base of 3.5 cm (7/2)

To work out the height, use Pythagoras’ theorem.

a^2 + b^2 = c^2 where c is the hypotenuse and a and b are the other two sides

7^2 - 3.5^2 = 36.75

Square root answer

= 6.06 cm

That’s the height of the triangle

Area of a triangle is base x height divided by 2

So 7 x 6.06 = 42.43…

/2

= 21.2 cm^2 to one d.p

Hope this helped!
Please mark Brainliest!!

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faust18 [17]

Answer:

40

Step-by-step explanation:

20 divided by 50% is 40

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2 years ago

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Answer:

The length= 16cm

The width= 6cm

The two long sides are 8cm both so 8 + 8 = 16

And the two short sides are 3cm both so 3 + 3 = 6

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3 years ago

NO LINKS!!! Part 2: Find the Lateral Area, Total Surface Area, and Volume. Round your answer to two decimal places.

slava [35]

Answer:

<h3><u>Question 7</u></h3>

<u>Lateral Surface Area</u>

The bases of a triangular prism are the triangles.

Therefore, the Lateral Surface Area (L.A.) is the total surface area excluding the areas of the triangles (bases).

$\implies \sf L.A.=2(10 \times 6)+(3 \times 6)=138\:\:m^2$

<u>Total Surface Area</u>

Area of the isosceles triangle:

$\implies \sf A=\dfrac{1}{2}\times base \times height=\dfrac{1}{2}\cdot3 \cdot \sqrt{10^2-1.5^2}=\dfrac{3\sqrt{391}}{4}\:m^2$

Total surface area:

$\implies \sf T.A.=2\:bases+L.A.=2\left(\dfrac{3\sqrt{391}}{4}\right)+138=167.66\:\:m^2\:(2\:d.p.)$

<u>Volume</u>

$\sf \implies Vol.=area\:of\:base \times height=\left(\dfrac{3\sqrt{391}}{4}\right) \times 6=88.98\:\:m^3\:(2\:d.p.)$

<h3><u>Question 8</u></h3>

<u>Lateral Surface Area</u>

The bases of a hexagonal prism are the pentagons.

Therefore, the Lateral Surface Area (L.A.) is the total surface area excluding the areas of the pentagons (bases).

$\implies \sf L.A.=5(5 \times 6)=150\:\:cm^2$

<u>Total Surface Area</u>

Area of a pentagon:

$\sf A=\dfrac{1}{4}\sqrt{5(5+2\sqrt{5})}a^2$

where a is the side length.

Therefore:

$\implies \sf A=\dfrac{1}{4}\sqrt{5(5+2\sqrt{5})}\cdot 5^2=43.01\:\:cm^2\:(2\:d.p.)$

Total surface area:

$\sf \implies T.A.=2\:bases+L.A.=2(43.01)+150=236.02\:\:cm^2\:(2\:d.p.)$

<u>Volume</u>

$\sf \implies Vol.=area\:of\:base \times height=43.011193... \times 6=258.07\:\:cm^3\:(2\:d.p.)$

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Lesechka [4]

You could use simple factoring to solve this. You would factor out a 7 and then have

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4 years ago