Question

The figure below shows a triangular wooden frame ABC. The side AD of the frame has rotted and needs to be replaced:

Triangle ABC has length of BC equal to 14 inches. A line segment DC joins the point D on AB with point C. Measure of angle ABC is 90 degrees, ACD is 15 degrees and measure of angle DCB is 30 degrees.

What is the length of the wood that is needed to replace AD?

Answer 1

@rohan

Answer 2

8.1 inches
6.2 inches
5.9 inches
7.4 inches

Answer 3

@MrNood

Answer 4

Can anyone help me?

Answer 5

Looking at it. It this trigonometry (precalculus)?

Answer 6

Nope, geometry. The make us do a lot of different things. Kinda sucks, especially if you want to go into another field of study that isnt math.

Answer 7

@mjdennis

Answer 8

I have a poor connection and only a few minutes to help you. Please be patient.
Geometry, you should know how to find AB, because of the big angle, 30+15 = ___ degrees.
And you should be able to find DB. Do you remember the relationships of a triangle with a 30 degree angle?

Answer 9

Solve DB, using the Tan Function.
Subtract the result from 14, as AB is also 14 same as BC as both are opposite 45 degree angle.

Answer 10

Nope. and sorry btw

Answer 11

Angle ACB is 45 degrees (30 + 15), so angle BAC has to be 45 degrees also. that means side AB equal side BC (opposite equal angles). Get to work.

Answer 12

Still (sadly) dont undestand

Answer 13

im not good with math

Answer 14

What do you not understand? Do you know what the sum of the interior angles of a triangle are?

Answer 15

Haha nope -.-

Answer 16

@rohan

Answer 17

Do you see that triangle ABC is an isosceles right triangle with both angles summing up 90 as well as the right angle which is given as 90 degrees making a total of 180 degrees?

Answer 18

yup, what happened? Sorry, was in class.

Answer 19

Lol its fine. Can you help me? I understood what you explained last so mabe you can help me with this one

Answer 20

If you intend to work problems such as these, you must first learn the basics of a triangle.

Answer 21

Yes, I know the basics.

Answer 22

Okay! I will try! @WalkingContradiction

Answer 23

Thank you!

Answer 24

its using the same concepts again. Can you apply the trig functions here

Answer 25

can you?

Answer 26

not really

Answer 27

haha im stupid

Answer 28

You're not, lets get this straight.

Answer 29

We need to find AD

Answer 30

yup

Answer 31

consider two triangles..
One with angle 30 deg and another with 30+15

Answer 32

ok...

Answer 33

Now try using tan function.. let AB=x and AD=y

Answer 34

uhhhhh

Answer 35

Now try doing it, I will help you if you get stuck

Answer 36

yeah, i cant do it. like, i legit dont understand HOW im passing geometry.

Answer 37

Wait bro.. What do we know about some basic function on trignometry.. I'll put the basic quickly
Sin, Cos and Then tan, Tan=Sin/Cos

Do you get the basic..