Question

Find the area of an isosceles triangle with one of its equal side is 5cm and perimeter is 18cm
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Answer 1

Answer:

90 cm is the area of an isosceles triangle with one of its equal side is 5 cm and perimeter is 18cm

Answer 2

Answer:

hey here is ur answer

so here we go

pls do refer reference figure which I have uploaded above

Step-by-step explanation:

so now as triangle is isoceles triangle

perimeter of isoceles triangle is

perimeter=2 times congruent side+base

ie 18=(2×5)+base

so solving we get

base=8 cm

now area of isoceles triangle=base×height upon 2

now we need to find its height so we need to do some construction ie join ad and bc

so then bd=dc=4 cm

so then by pythagoras theorem

now applying

ab square=ad square+bd square

thus (5)square=ad square+(4) square

solve it you get ad=3 cm

now substitute it in area formula

so area of isoceles triangle is base ×height upon 2

ie 8×3/2

thus 24 upon 2 =12 sq cm

hence area of isoceles triangle=12 square.cm