If the sine of the apex angle of an isosceles triangle is five thirteenths, then the cosine of its b

In two cases, set the top angle angle to 2x

sin2x=5/13

That is, 2sinxcosx=5 13 and (sinx) 2+(cosx) 2=1

Get (sinx+cosx) 2=18 13

sinx-cosx)^2=8/13

1.When the apex angle is acute: 00, sinx-cosx<0 gives sinx = 26 26 26 The cosine value of the base angle is equal to the value of sinx, which is also 26 26

2.When the apex angle is obtuse: 00, sinx-cosx>0 gives sinx=5 26, and the cosine value of the base angle is equal to the sinx value, which is also 5 26

Hello, glad for your question.

The triangle is an isosceles triangle.

Top angle = -2 bottom angle.

sin apex angle = 5 13

cos apex angle = root number under (1-sin apex angle) = 12 13 when cos apex angle = 12 13:

2cos bottom angle -1=cos( -apex angle) = cos2 bottom angle.

cos bottom angle = (1 + cos( -apex angle)) 2 = (26 under the root number) 26 when cos apex angle = -12 13:

Let the bottom angle of the isosceles triangle be 180°-2, then the top angle of the banquet mold is 180°-2, and it is known that cos(180°-2 )=3 and 5, then cos2 = 1-2sin =3 5, and the wheel buried sin = 1-3 5) 2=1 5, because it is the bottom angle of the isosceles triangle, so 0° 90°, sin = 1 5) = 5 5.

Let the sine value of the base angle be 4 5=k

The waist is 5k, and the height on the edge of the ground is 4k

The bottom half is 3k, and the total length is 6k

The hand carries half of the top corner, Bi Xun is set to conceal a, then cosa=3 5cos2a=2(cosa) squared -1=-7 25

Let the bottom angle of the wheel be a, and the top angle is 180-2a, and it is known that sina =

cos(180-2a)=-cos2a=-1+2sin 2a=Hey brother and friend again!

Let the bottom angle be , be the acute angle, then the top angle is 180 -2 sin =5 13, cos =12 13

The sine of the apex angle:

sin2 = 2sin cos = 120 169 cosine of the apex angle.

cos2 = 2sin -1 = -119 tangent of 169 vertex angle:

tan2α=-120/119

There are two scenarios.

Set the top angle to 2x

sin2x=5/13

i.e. 2sinxcosx = 5 13

and (sinx) 2+(cosx) 2=1 to get (sinx+cosx) 2=18 13

sinx-cosx)^2=8/13

1.When the apex angle is acute: 00, sinx-cosx<0 gives sinx = 26 26

The cosine value of the bottom angle matches the value of sinx, and the god equal is also 26, and the slip grip is 262When the apex angle is obtuse: 00, sinx-cosx>0 gives sinx=5 26 Xinmeiqing 26

The cosine value of the bottom angle is equal to the sinx value, which is also 5 26 26

If the base angle is a, then the top angle is -2a

cos(π-2a)=1/3

cos2a=1/3

i.e. cos2a=-1 talk volt3

cos2a=1-2sin²a

1-2sin²a=-1/3

sin²a=2/3

Contains filial piety with sina>0

sina = Shen 6 3

That is, the sine value of the bottom angle is 6 3