AB？ =? AC？ =? 6,

Through point a as AD⊥BC in d,

AD？ =? h，

BD？ =? DC？ =? x，

Judging from the title:

xh= 12，

From Pythagorean Theorem: X? +? h^？ =? 36,

Put xh? =? 24 into x? +? h^？ =? 36 Must:

x^？ +? h^？ =? 3xh/2，

∴2h^？ -? 3xh？ -? 2x^？ =? 0,

Divide both sides by x:

2(h/x)^？ -? 3h/x？ -? 2? =? 0,

Take (h/x) as a whole, and get it by finding the root formula:

h/x？ =? 2 (I will omit the negation)

∴ The tangent of the base angle is 2,

What they did was wrong! )

2. Make a symmetrical point P of point E about AC. Obviously, p is on AD.

Connect PB to AC to f,

EF at this time? +? BF？ At the very least,

Number three, number three,

3. In Rt△ABC, ∠ c = 90,

Let the opposite sides of angles a, b and c be a, b and c respectively.

∴sinA？ =? Air conditioning?

Tana? =? a/b

∵ Sina Yi? +? Tana 1 =5

∴c/a？ +? b/a？ =? 5,

∴b？ +? c？ =? 5a，

From Pythagorean Theorem:

a^？ +? b^？ =? c^，

Play b? +? c？ =? Replace a with 5a? +? b^？ =? Merge and simplify:

13(b/c)^？ +? b/c？ -? 12? =? 0,

Considering b/c as a whole, it is obtained from the bulbous formula:

b/c？ =? 12/ 13,

∴cosA？ =? 12/ 13,

4. Solution: ∵ The zeroth power of any non-zero real number is 1.

∴(√3- 1) is 1.

The answer is detailed enough!