The height on the base edge of an isosceles triangle is equal to the length of the base edge, and th

Is the cosine value theorem ever over? Cos angle a = (b square + c square - a square) 2 times bc

In this problem, the height is h, then the bottom is h, (the height of the isosceles triangle divides the base into half) the half of the base is (1 2) h, according to the right triangle theorem, the waist length is (5 2) h under the root number.

At this time, the cosine value of the apex angle = [(5 4) h square + (5 4) h square - h squared] 2 * (5 4) h square = 3 5

Set the height to x and the bottom edge to x

From the Pythagorean theorem, the waist is (the root of 2 is 5)x

Then by the cosine theorem cos@ = ((5 4) (x) square + (5 4) (x) square - x squared) 2 (5 4) (x) squared.

cos@=3/5

Draw a diagram, compare the size to know the cosine value of half of the apex angle, and then use the cos2a=2(cosa)*2-1 theorem! Answer.

From the question: ad=bc, ad is perpendicular to bc, ab=ac, let: a=2$, then dac=$;

dc=a, then ad=2a, ac=root 5 times a, so: cos$=2/5 of the root, sin$=1/5 of the root, so, cosa=cos2$=3/5

Use the Pythagorean to find the waist length, and then use the cosine theorem.

Set the height to x and the bottom edge to x

From the Pythagorean theorem, the waist is (2 parts of the bright root number 5)x

Then the cosine theorem cos@=(5 4)(x) squared + (5 4)(x) squared - x flat squared) 2 (5 4) (x) squared.

cos@=3/5

Let the height be x, and the bottom edge is also x The waist is (5)x by the root of 2 x and then by the cosine theorem cos@=(5 4)(x) square + (5 4)(x) flat mode letter square shed manuscript chain filial piety-x squared) 2 (5 4) (x) square cos@ = 3 5

Let the lead tremor of the long ridge at the bottom be B, and the bottom cherry blossom will be A

Rule. Height on the waist = bsina

Height on the bottom edge = b 2) tana

According to the title. 2bsina = b/2)tana4sina = tana

cosa = 1/4

sina = 1-1 16) (1 2) = root number 15) 4

According to the equal area, the length of the waist is equal to the length of the bottom side, and the stupid brigade is a triangle of positive width.

The bottom angle is 60 degrees.

The root of 2 is No. 3

Draw a triangular line first, make the height on the bottom edge, then the vertical foot is the midpoint of the bottom edge, and the height is the bisector of the top big call angle, let the bottom edge length be a, by the Pythagorean theorem, it can be known that the waist length is the root of half 5*a, and the cos value of the top angle can be known from the cosine theorem is 3 Roll shirt Kai 5

Angles a, b, and c correspond to side lengths a, b, and 2c, respectively

The isosceles is set to a=b, so the apex angle is c, and the height is 2c, so cos(c2) is equal to (2c) than the sum of the squares of 2c and c under the upper root number.

It is equal to 2 and 5 below the previous root number

According to the cosine theorem, cos(c) is equal to twice the square of cos(c2) minus 1 to solve cos(c)=3 5

Solution: Let the slope height be h

According to the conditions, the base length of the isosceles triangle is 6 2 = 12, and the height is 8 according to the formula of equal area: 12 8 2 = 10 h 2h=