Math

Which of the following values best approximates of the length of c in triangle ABC where c = 90(degrees), b = 12, and B = 15(degrees)?

c = 3.1058
c = 12.4233
c = 44.7846
c = 46.3644

In triangle ABC, find b, to the nearest degree, given a = 7, b = 10, and C is a right angle.

35(degrees)
44(degrees)
46(degrees)
55(degrees)

Solve the right triangle ABC with right angle C if B = 30(degrees) and c = 10.

a = 5, b = 5, A = 60(degrees)
a = 5, b = 8.6602, A = 60(degrees)
a = 5.7735, b = 11.5470, A = 60(degrees)
a = 8.6602, b = 5, A = 60(degrees)

I'm horrible at trig and I do not know how to do this, please help?

  1. 0
  2. 0
  3. 54
asked by Max
  1. "I am horrible at trig" is a cop-out.

    All you have to remember in a right-angled triangle is 3 pairs of sides combinations for the primary trig functions.

    Memorize the following word: SOH-CAH-TOA
    SOH -- SinØ = Opposite/Hypotenuse , not the S,O, and H
    CAH --CosØ = Adjacent/Hypotenus
    TOA -- TanØ = Opposite/Hypotenuse

    The other notation you should know that in labeling triangles, capital letters are usually used for the angles and small letters would be the sides opposite those angles.
    Draw a right-angled triangle ABC, label it that way, and MEMORIZE the above, you are "horrible" at it only because you have not made the effort to learn this.

    The first one:
    Which of the following values best approximates of the length of c in triangle ABC where C = 90°, b = 12, and B = 15° ? (notice c ---> C, since C is an angle)

    So in terms of the 15° angle , b is the Opposite and c is the Hypotenuse
    so "opposite - hypotenuse" form SOH-CAH-TOA suggests sin

    sin 15° = 12/c
    c sin15 = 12
    c = 12/sin15° = 46.3644

    after doing a few, you can do each in 3 or less lines

    #2, this time you are not given any angles, but you are given 2 sides
    "In triangle ABC, find B, to the nearest degree, given a = 7, b = 10, and C is a right angle. " (notice I changed b --> B)

    make your sketch , in terms of angle B, we are given the opposite and the adjacent, so that suggests tan
    tanB = 10/7 = ....
    B = 55° , see that? only 2 lines of actual work

    (on my calculator, I did the following:
    10÷7 =
    2ndF
    tan
    =
    and I got 55.0079.... )

    try the rest, they are easy

    by solving a triangle, you are finding all the missing sides and missing angles.
    remember, in a right-angles triangle as soon as you have one of the smaller angle, you also have the third since their sum must be 90°
    Also if you have 2 sides in a right-angled triangle you could also find the third by Pythagoras. This is often a good way to check your answers.

    1. 0
    2. 0
    posted by Reiny

Respond to this Question

First Name

Your Response

Similar Questions

  1. Trig

    Its a 30-60-90 triangle there's a line in the center that= 10 a. What is the length of the hypotenuse of triangle ABC? b. What is the length of the shorter leg of triangle ABC? c. What is the length of the longer leg of triangle

    asked by BreAnne on February 2, 2012
  2. Trigonometry/Geometry

    In most geometry courses, we learn that there's no such thing as "SSA Congruence". That is, if we have triangles ABC and DEF such that AB = DE, BC = EF, and angle A = angle D, then we cannot deduce that ABC and DEF are congruent.

    asked by Sam on November 19, 2013
  3. Precalculus

    In most geometry courses, we learn that there's no such thing as "SSA Congruence". That is, if we have triangles ABC and DEF such that AB = DE, BC = EF, and angle A = angle D, then we cannot deduce that ABC and DEF are congruent.

    asked by John on February 24, 2014
  4. maths

    Choose three options which are true: a) an angle of 150 degrees is equivalent to 2pie/3 radians. b) Cos 0 = cos (0 – pie/2) for al values of 0. c) Sin 0 = cos (0 – pie/2) for all values of 0. d) If triangle ABC has a right

    asked by sarah on May 20, 2007
  5. Geometry

    Let ABC be any triangle. Equilateral triangles BCX, ACY, and BAZ are constructed such that none of these triangles overlaps triangle ABC. a) Draw a triangle ABC and then sketch the remainder of the figure. It will help if

    asked by G on March 20, 2015
  6. Math

    In a triangle ABC,AB=5cm,BC=12cm,angle ABC=90°calculate 1)the length of AC. 2)the area of the triangle 3)the length of the perpendicular from B to AC

    asked by Anonymous on January 12, 2017
  7. Math

    the right triangle ABC, the altitude from vertex C divides the hypotenuse into two segments, one of length 2 and the other of length 16. Find the perimeter of triangle ABC.

    asked by Lily on December 7, 2013
  8. Centroids and Triangles - determining perimeter?

    Let G denote the centroid of triangle ABC. If triangle ABG is equilateral with side length 2, then determine the perimeter of triangle ABC. I drew the diagram, but it doesn't really help....

    asked by Knights on March 27, 2013
  9. Trig

    a. What is the length of the hypotenuse of triangle ABC? b. What is the length of the shorter leg of triangle ABC? c. What is the length of the longer leg of triangle ABC? angle A=60, angle B=30, angle C=90 the triangle has a

    asked by BreAnne on February 3, 2012
  10. HELP!!!!RIGHT NOW!!!!

    Which set of side lengths shows similar triangles? (1 points) A) Triangle ABC : 40, 20, 50; Triangle XYZ: 10, 4, 8 B) Triangle ABC : 30, 20, 60; Triangle XYZ: 40, 60, 90 C) Triangle ABC : 110, 80, 60; Triangle XYZ: 6, 8, 5.5 D)

    asked by Dezzy on April 29, 2011

More Similar Questions