(2013 the second mock exam) in Zhejiang, the vertices A and D of square ABCD with 1 sides of length are sliding on the X axis and the Y axis half and right (containing the origin) respectively. The maximum value of OB OC is "affirmative". ．

(2013 the second mock exam) in Zhejiang, the vertices A and D of square ABCD with 1 sides of length are sliding on the X axis and the Y axis half and right (containing the origin) respectively. The maximum value of OB OC is "affirmative". ．

Let ∠ oad = θ, ad = 1, so 0A = cos θ, OD = sin θ, as shown in the figure ∠ Bax = π 2 - θ, ab = 1, so XB = cos θ + cos (π 2 - θ) = cos θ + sin θ, Yb = sin (π 2 - θ) = cos θ, so ob = (COS θ + sin θ, cos θ) similarly, we can get C (sin θ, cos θ + sin θ), that is, OC = (s

Xiaoming goes from a to B along the road, and Mn is in two shopping malls on the same side of the road. Ask where to go and the shortest distance to the two shopping malls

This problem should be the same as the mirror reaction in physics. Make a straight line through point m, mm 'perpendicular to the intersection of AB is O, and Mo = m'o. connect M'n to the intersection of AB and o', then the route from point o 'to two companies is the shortest

As shown in the figure, the distance between a and B on the railway is 25km, C and D are two villages, Da ⊥ AB is in a, CB ⊥ AB is in B, known Da = 15km, CB = 10km, now we need to build a local product acquisition station E on the railway AB, so that the distance between C and D villages and E station is equal, then how many kilometers should e station be built from a station?

Let AE = XKM, ∵ C and D villages have the same distance to e station, ∵ de = CE, that is, de2 = CE2. According to Pythagorean theorem, we can get 152 + x2 = 102 + (25-x) 2, x = 10. Therefore, e point should be built 10km away from a station

There are two villages m and N on both sides of the straight road ab. now we plan to build a station P on the ab road to make the distance between the station and the two villages equal. What should we do

Connect two points m and N, make the middle vertical line of Mn line, let AB intersect at O, then make a circle with O, a and B are on the circle, OK