Special Right Triangles
Need help don’t understand this.

fourth option

Step-by-step explanation:

Since the sides are congruent, then the diagonal divides the square into 2 right isosceles triangles.

Thus the 2 base angles are congruent with measure 45°

Hence y = 45

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Using the cosine ratio in the right triangle and the exact value

cos45° = , then

cos45° = = = ( cross- multiply )

2x = 10 ( divide both sides by 2 )

x = 5

step-by-step explanation: 4 cause 2+2=4