Cho hình chóp SBCDA có đáy ABCD là hình vuông cạnh a , mặt bên (SAD) vuông góc vs (SAD) và SAD là tam giác đều . M là trung điểm của AD . Tính góc giữa (SAB) với (ABCD)

The u-drive rent-a-truck company plans to spend $13 million on 320 new vehicles. each commercial van will cost $25 comma 000, each small truck $50 comma 000, and each large truck  $80 comma 000. past experience shows that they need twice as many vans as small trucks. how many of each type of vehicle can they buy?

Celeste wants to have her hair cut and permed and also go to lunch. she knows she will need $50. the perm cost twice as much as her haircut and she needs $5 for lunch. how much does the perm cost?

Annabelle's homework is 75% it took her three hours how long should she estimate it will take her to complete her homework.