（4tan30°)(5sin60°)-6cos60°​

7

Step-by-step explanation:

Using exact values

(4tan30°)(5sin60°) - 6cos60°

= 20tan30°sin60° - 6cos60°

= 20 × × - 6 ×

= - 3

= 10 - 3

= 7

no not all of them.

step-by-step explanation:

some of them have a square base.

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,