In the triangle ABC, the angle ACB is equal to 90 degrees, the points E and F are on the edge AB, and the angle CEB = angle ECB, the angle CFA = angle FCA, and the degree of the angle ECF is calculated
∵∠ACB=90
∴∠A+∠B=90
∵∠CEB=∠ECB
∴∠ECB=(180-∠B)/2
∵∠CFA=∠FCA
∴∠FCA=(180-∠A)/2
∴∠BCF=∠ACB-∠FCA=90-(180-∠A)/2=∠A/2
∴∠ECF=∠ECB-∠BCF=(180-∠B)/2-∠A/2=(180-∠A-∠B)/2=(180-90)/2=45°
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