Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Which is equal to sin75\sin 75^\circ? \newlineChoices: \newline(A) cos25\cos 25^\circ\newline(B) cos15\cos 15^\circ\newline(C) sin25\sin 25^\circ\newline(D) sin15\sin 15^\circ

Full solution

Q. Which is equal to sin75\sin 75^\circ? \newlineChoices: \newline(A) cos25\cos 25^\circ\newline(B) cos15\cos 15^\circ\newline(C) sin25\sin 25^\circ\newline(D) sin15\sin 15^\circ
  1. Recognize Sum of Angles: Recognize that sin75\sin 75^\circ can be expressed as the sum of two angles for which we know the sine and cosine values. The sum of angles formula for sine is sin(a+b)=sin(a)cos(b)+cos(a)sin(b)\sin(a + b) = \sin(a)\cos(b) + \cos(a)\sin(b). We can express 7575^\circ as the sum of 4545^\circ and 3030^\circ, which are angles we know the sine and cosine values for.
  2. Apply Formula to sin75°\sin 75°: Apply the sum of angles formula to sin75°\sin 75°. We have sin75°=sin(45°+30°)=sin(45°)cos(30°)+cos(45°)sin(30°)\sin 75° = \sin(45° + 30°) = \sin(45°)\cos(30°) + \cos(45°)\sin(30°). We know that sin(45°)=cos(45°)=2/2\sin(45°) = \cos(45°) = \sqrt{2}/2, sin(30°)=1/2\sin(30°) = 1/2, and cos(30°)=3/2\cos(30°) = \sqrt{3}/2.
  3. Substitute Known Values: Substitute the known values into the formula. This gives us sin75°=(22)(32)+(22)(12)=(64)+(24)\sin 75° = (\frac{\sqrt{2}}{2})(\frac{\sqrt{3}}{2}) + (\frac{\sqrt{2}}{2})(\frac{1}{2}) = (\frac{\sqrt{6}}{4}) + (\frac{\sqrt{2}}{4}).
  4. Simplify Expression: Simplify the expression. We can combine the fractions to get sin75=(6+2)/4\sin 75^\circ = (\sqrt{6} + \sqrt{2})/4.
  5. Recognize Matching Trigonometric Function: Recognize that the value of sin75\sin 75^\circ we found must be equal to one of the trigonometric functions of the angles given in the choices. We need to find which one matches (6+2)/4(\sqrt{6} + \sqrt{2})/4.
  6. Compare to Choices: Compare the value of sin75°\sin 75° to the choices. We know that sin(90°x)=cos(x)\sin(90° - x) = \cos(x), so sin75°=cos15°\sin 75° = \cos 15°. Therefore, sin75°\sin 75° is equal to cos15°\cos 15°.

More problems from Sine and cosine of complementary angles