Question

E

1)
AC = 9 cm
AB = 3 cm
DE = 20 cm
Angle ABC = angle CBD= angle BDE = 90°
20 cm
9 cm
Calculate the length of CD.
Give your answer to 3 significant figures.
50°
А
D
→B
3 cm

Please could you could give me a step by step.

Answer 1

Explanation:

We can use Hypotenuse Theorem for this:

For triangle ABC,

AC²=CB²+BA²

9²=CB²+3²

Switch the sides

-CB²=3² -9²

-CB²= 9-81

-CB²= -72

the signs cut each other

CB²=72

the square changes sides

CB=√72

CB= 8.49 cm

Now triangle CBD

We have the length of CB but not the other two whereas we have the angle

It will be sin

As we know sin= O/H

Here O is CB whereas H is CD

Put the values

sin 50= 8.49/H

H= 8.49 ÷sin 50

Calculate

H=11.1 cm

As we know H is CD so CD is 11.1 cm

Hope it helps