one Angle is a 45 degree right Angle trigonometric, that is, the isosceles right Angle trigonometric, that is, the other acute Angle is also 45 degrees, the two right angles are equal to, if the Length of side of the right Angle is 1, Then the skew Length of side is √2, so the ratio of the three sides is 1:1:√2

45 ̊ Rad π/4 Sine 0.707107 Cosine 0.707107 Tangent 1 Cotangent 1