Current location - Training Enrollment Network - Mathematics courses - Fujian 20 10 Mathematics and Physics College Entrance Examination 2 1 The solution of the second question about coordinate system and parameter equation had better be more detailed. Thank you.
Fujian 20 10 Mathematics and Physics College Entrance Examination 2 1 The solution of the second question about coordinate system and parameter equation had better be more detailed. Thank you.
( 1)

ρ=2√5sinθ

Multiply both sides by p at the same time.

ρ? =2√5ρsinθ

∴x? +y? =2√5y (#)

x? +(y-√5)? =5

(2)

Parametric equation of straight line L, note that L passes through P(3, √5).

{ x = 3-√2/2 * t; y=√5-√2/2*t

Note that l passes through P(3, √5), M(x, y) is on l, and t=PM.

Replace (#) to get:

(3-√2/2t)? +(√5-√2/2t)? =2√5(√5-√2/2t)

Finishing:

t? -3√2t+4=0

Let the parameter values corresponding to the intersection points A and B of a straight line L and a circle C be T 1 and T2, respectively.

Then t 1+T2 = 3 √ 2, t 1t2 = 4 > 0, t 1, T2 with the same sign.

|PA|=|t 1|,|PB|=|t2|

∴|pa|+|pb|=|t 1|+|t2|=|t 1+t2|=3√2