Need big explain how you got the answer.

Step-by-step explanation:

This is a right triangle with the 90 degree angle identified at D and the 60 degree angle identified at B. Because of the triangle angle sum theorem, the angles of a triangle all add up to equal 180 degrees, so angle C has to be a 30 degree angle.

There is a Pythagorean triple that goes along with a 30-60-90 triangle:

( x , x√3 , 2x )

where each value there is the side length across from the

30 , 60 , 90 degree angles.

We have the side across from the 90 degree angle, namely the hypotenuse. The value for the hypotenuse according to the Pythagorean triple is 2x. Therefore,

2x = 2√13

and we need to solve for x. Divide both sides by 2 to get that

x = √13

Now we can solve the triangle.

The side across from the 30 degree angle is x, so since we solved for x already, we know that side DB measures √13.

The side across from the 60 degree angle is x√3, so that is (√13)(√3) which is √39.

And we're done!

12

step-by-step explanation:

12 + 5 = 17

12x2=24

24-7=17