## Qwerty90 Group Title What is the length of Segment AB to the nearest tenth of a meter? 2 years ago 2 years ago

1. Qwerty90

2. UnkleRhaukus

$AB=AD+DB$ $\cos(60°)=\sin(30°)=\frac{AD}{14}$ $\sin(60°)=\cos{(30°)}=\frac{DC}{14}$

3. Qwerty90

Do I then need to use the sin and cosine formula to figure the rest out?

4. UnkleRhaukus

i still cannot see myself how to get DB

5. Qwerty90

lets assume its 30

6. UnkleRhaukus

very rough DB~7

7. Qwerty90

what do the first two equal?

8. UnkleRhaukus

actually you can work out angle DCB with a trig identity, because be know two of the sides, and then use another trig identity to find DB

9. UnkleRhaukus

the first two what? @Qwerty90

10. Qwerty90

when you gave those first few ratios.. the AD/14 and DC/14 what do those equal

11. UnkleRhaukus

you dont know the values of sin 30=cos60? you must remember theses if you dont remember you can use a calculator

12. Qwerty90

yes i know those..

13. UnkleRhaukus

$\sin60°=\cos30°$ is a little bit tricker on a calculator, because the value given is irrational but you can square the output 0.86602540... 0.86602540...^2=0.75=3/4 so $\sin60°=\cos30°= \sqrt{\frac{3}{4}}=\frac{\sqrt3}2$