# Thread: Needing help with angle of evaluation

1. ## Needing help with angle of evaluation

(a) When the angel of elevation of the sun is 62 degrees, the shadow cast by a vertical pole is 10m long. Find the height of the pole correct to one decimal place.

(b) If a=8, c=5 and A=72 degrees, find the size of the angle C?

(c) A ladder is 7m long and reaches 5m up a vertical wall. Find the angle between the ladder and the horizontal.

(d) Find the area of the triangle shown in the diagram:

Thanks a million!

2. ## Re: Needing help with angle of evaluation

Originally Posted by Molly1313

(a) When the angel of elevation of the sun is 62 degrees, the shadow cast by a vertical pole is 10m long. Find the height of the pole correct to one decimal place.

make a sketch ... use the tangent ratio

(b) If a=8, c=5 and A=72 degrees, find the size of the angle C?

make a sketch ... use the law of sines

(c) A ladder is 7m long and reaches 5m up a vertical wall. Find the angle between the ladder and the horizontal.

make a sketch ... use the sine ratio.

(d) Find the area of the triangle shown in the diagram:

if 8 is the base of the triangle, then the height of the triangle is 6sin(52)
...

3. ## Re: Needing help with angle of evaluation

Originally Posted by Molly1313

(a) When the angel of elevation of the sun is 62 degrees, the shadow cast by a vertical pole is 10m long. Find the height of the pole correct to one decimal place.
Draw a sketch! You are dealing with a right triangle. Use the tan-function: $\tan(62^\circ) = \frac{length\ of\ pole}{10\ m}$

(b) If a=8, c=5 and A=72 degrees, find the size of the angle C?
Draw a sketch! Use the Sine-rule.

(c) A ladder is 7m long and reaches 5m up a vertical wall. Find the angle between the ladder and the horizontal.
Draw a sketch! You are dealing with a right triangle whose hypotenuse is 7 m long. Use the Sine-function.

(d) Find the area of the triangle shown in the diagram:

Thanks a million!
The area of a triangle is calculated by:

$a = \frac12 \cdot 8\ cm \cdot h_{of\ the\ base}$

Draw the height of the base into your sketch. You are now dealing with a right triangle. Use the Sine-function: $\sin(62^\circ)=\frac h6$
Solve for h. Plug in this term into the equation of the area.