Answer:
Right angled isosceles triangle.
Explanation:
To cut a square into identical triangle one need to draw a diagonal for the square.
Suppose ABCD is the square then AC is one diagonal.
The two triangles will be
ABC and ADC
ABC has sides AB , BC and AC
ADC has sides AD, DC, AC
Since ABCD is a square its sides AB, BC , CD , DA are equal hence
for triangle ABC and ADC
side AB , BC and AD, DC will be equal
also AC is common side hence third side of both triangle is also equal .
Hence ABC and ADC are identical triangle.
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for triangle ABC
two sides are same in length and third is different
for triangle ABC, AB = BC but AC is not equal to AB and AC
and angle ABC is right angled as it angle of square
As two sides are equal and one angle is right angled
hence triangle ABC is right angled isosceles triangle
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for triangle ADC
two sides are same in length and third is different
for triangle ADC, AD= DC but AC is not equal to AD and DC
and angle ADC is right angled as it angle of square
As two sides are equal and one angle is right angled
therefore triangle ADC is right angled isosceles triangle
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To understand the solution we need to draw square ABCD and diagonal AC to have better visual understanding of solution.