Use special right triangles to find the exact value (no decimals).

1) sin 60°
2) tan 60°
3) cos 30°
4) sin 45°

can someone explain? i don't get it.

Let’s find some exact values using some well-known triangles. Then we’ll use these exact values to answer the above challenges.

sin 45°: You may recall that an isosceles right triangle with sides of 1 and with hypotenuse of square root of 2 will give you the sine of 45 degrees as half the square root of 2.

sin 30° and sin 60°: An equilateral triangle has all angles measuring  60 degrees and all three sides are equal.  For convenience, we choose each side to be length 2.  When you bisect an angle, you get 30 degrees and the side opposite is 1/2 of 2, which gives you 1.  Using that right triangle, you get exact answers for sine of 30°, and sin 60° which are 1/2 and the square root of 3 over 2 respectively.

Now using the formula for the sine of the sum of 2 angles,

sin(A + B) = sin A cos B + cos A sin B,

we can find the sine of (45° + 30°) to give sine of 75 degrees.

We now find the sine of 36°, by first finding the cos of 36°.

The cosine of 36 degrees can be calculated by using a pentagon.

that is as much as i know about that.

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.