It is known that the right focus of the hyperbola x2 / 9-y2 / 16 = 1 is F1, F2, the point P is on the left point of the hyperbola, and the absolute value of Pf1 multiplied by the absolute value of PF2 is equal to 32, so the size of the angle f1pf2 is calculated

It is known that the right focus of the hyperbola x2 / 9-y2 / 16 = 1 is F1, F2, the point P is on the left point of the hyperbola, and the absolute value of Pf1 multiplied by the absolute value of PF2 is equal to 32, so the size of the angle f1pf2 is calculated

Let MF1 = R1, MF2 = R2, R1 * R2 = 32, R1-R2 = - 6, square of both sides, (R1-R2) ^ 2 = 36, then R1 ^ 2 + R2 ^ 2 = 100, cosine value, R1 ^ 2-r2 ^ 2 - (2C) ^ 2 = 0, so it is 90 degree