trong không gian, cho hình chóp OABC có OA, OB, OC đôi 1 vuông góc và cùng độ dài a. Chứng minh rằng OA vuông góc BC

Ac contractor is building a new subdivision outside of the city. he has started work on the first street and is planning on the other streets to run in a direction parallel to the first. the second street will pass through (-2,4) find the equation of the location of the second street in standard form. a.2x+y=2 b. x-y=2 c.2x+y=2 d.x+y=2

Simplify the expression and find the missing terms. the simplest form of has in the numerator and in the denominator.

Jack has a piece of red ribbon that is two times as long as his piece of blue ribbon. he says that he can use two different equation to find out how long his piece of red ribbon is compared to his piece of blue ribbon is. is he correct? explain his reasoning