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!!
